Valoran = Earth, will we get a Spanish-speaking champion or Spanish-speaking nation?
Basically, I think Valoran is what a modern Pangaea would look like if all the continents (from Earth) merged together again. Each champion has his or her own unique trait, personality, and appearance that signifies what they are a reference to (i.e. Lucian is a reference to African Americans, Twitch a reference to the Black Plague, etc.).
Before I get down to this theory, I just want to say WARNING Prepare to go through a lot of texts. If you truly care, then you would read this thoroughly. Also, as to RiotGames, I don't mean any disrespect or intend on any racism. Just stating my opinions based on what I discovered.
Now, on to the theory: I believe that Valoran is based on many of our real-world continents (such as Asia and Europe) and other literal myths (such as Bigfoot, paranormal activity, martians, etc.). Even though is the answer is obvious to many veteran players, did you ever ask yourself this " If League of Legends consists of different champions based on several ethnicities and races, there why hasn't there been a Latin-American champion or at least a region dedicated to South America? "
Q: "What makes you think that Valoran is based on Asia, USA, or insert country here? A: The answer is quite obvious when you start looking at each of Valoran's regions and the champiosn that reside there:
Demacia Quote taken from lore
The largest city in the Kingdom, the capital is the main political, cultural, religious, military, economic and educational center of the country.
The United States of America, not to say we are superior or the greatest, is the "land of the immigrants" and country where people are given freedom of speech, choice, and rights. Also, in terms of culture and religion, USA is also divert.
Quote taken from lore
Along the western coast of Valoran, the human nation of Demacia shines as the continent's paragon of virtue amongst all the other human settlements. The residents are always striving to sharpen their bodies and minds in the pursuit of absolute justice.
Dozens of people, whether it be an immigrant, family relative, or even U.S. born resident, all came or are living here for a reason: To better themselves. Based on speculation, people come to America to start a new beginning and to get away from their countries and Demacia (just like USA) appears to be the ideal place to live for people who just want to make a fresh start.
As for Demacian residents, there is a diversity among the citizens:
Fiora, apparently has a French heritage, but despite this, she is a native to Demacia. Literally speaking, she would be considered French-American?
Lucian, reference to an African American, native to Demacia.
Garen, reference to the stereotypical "white" or a more appropriate term Caucasian. native to Demacia.
Lux, reference to the stereotypical "white" or a more appropriate term Caucasian. Sister to Garen, also a native to Demacia.
Xin Zhao, a resident of Demacia, but not born there. His origins and birthplace are unknown. His lore assums that it might be Zaun, but based on his appearance it could be Ionia. Speaking of which, we will move on to Ionia.
Ionia It is as clear as fresh water that Ionia is indeed a reference to the Middle East and Asia.
Quoted from Ionia's Culture
The island nation of Ionia is a haven for beings who seek spiritual evolution and enlightenment. While populated primarily by humans, some yordles and beings of unique origin also make Ionia their home. There are many spiritual centers and schools of enlightenment in Ionia, each one working in harmony with one another to find the answers to life’s mystical questions. Why are we here? Who are we? What does life truly mean? Such pursuits leave little time for thoughts of imperialism; the Ionians are extremely peaceful by nature.
Reference to China and its take on religions such as Buddhism and Taoism as well as also being a reference to Japan and other Asian countries.
Links: http://www.livescience.com/28823-chinese-culture.html
http://en.wikipedia.org/wiki/Tao
http://iml.jou.ufl.edu/projects/Spring01/Newsome/culture.html
In addition, many of Ionian champion's quotes sound like ancient Chinese proverbs and lines you'd get out of a fortune cookie.
The eyes never lie. Find your center. Blade and body. Do not fear the unknown. Hesitation is the seed of defeat.
Now to get to the champions and their traits:
Lee Sin, born in Ionia, reference to Tibetan and Buddihist monks.
Ninjas born and originate from Ionia. Ninjas are agents that originated from Japan.

Ahri, The nine-tailed fox. Character appearance based on fox spirits common in East Asian mythology.
Wukong, his character description is based on the character from "Journey to the West".
Final region I'd like to point out at is Zaun. My assumption of Zaun is that the region is based on Northern Europe in a post-apocalyptic and pandemic setting populated by crazy, insane citizens, as is the case with
Jinx and
Singed.
Quote from Zaun's culture
While known to be a notoriously self-centered people by other nations, the denizens of Zaun collectively take great pride in themselves and their city. To them, their right to do as they please is what makes Zaun the freest city-state on Runeterra. As a result the streets of Zaun are a constant hive of activity. Shopkeepers with a variety of eccentric items can be found at every corner of the city, with the dark and seedy alleys overflowing with ambitious individuals willing to give their all for a profit. It's also said that corporate rivalry is the very spirit of competition that defines Zaun as a city-state. Nevertheless, both espionage and sabotage are considered common practices when doing business with Zaunites.
Zaun is a dystopian, fearful idea of what Europe would look like if Adolf Hitler and the Nazis would continuously engage in war with the other countries during World War II. Furthermore, to support my speculation as to why I consider Zaun a part of Northern Europe, I will bring to you the Zaunite champions:
Mundo, "Dr. Mundo is a reference to "Mr. Hyde", the abominated alter ego of Dr. Henry Jekyll from the 1886 book by Robert Louis Stevenson" taken from LOL wikia. Also, keep in mind the book takes place in England.
Twitch, champion title is "The Plague Rat". Reference to the Bubonic Plague i.e. the Black Plague.
Singed, possible reference to Fritz Haber, who is a German chemist. Singed might also be a reference to the mad scientist who made Frankenstein (Link: http://en.wikipedia.org/wiki/Frankenstein ).
Viktor might also be a reference to this.
As for the other nations and regions, I'm just gonna end it here because it could possibly take hours to go in-depth on each area of Valoran, their cultures, and champions. However, I point out that Shurima is a reference to Egypt hence the motif being desert and sand. Also, the champions that reside there
Renekton,
Nasus, and Azir are all based on Egyptian Gods.
Now, my question from earlier was this "** If League of Legends consists of different champions based on several ethnicities and races, there why hasn't there been a Latin-American champion or at least a region dedicated to South America?** " Is Riot still thinking of adding a Spanish champion or will we get a Latin-American based area where citizens salsa dance, listen to upbeat music, and respect the dead?
) and armadillos (Rammus
) are South America