Why League is not dying, per se (that'll take a loooonggg time), but peaking
As we know, since about mid season 3 the boards community has grown more and more angry about the changes that Rito has been making. However, this is not why I say this game has peaked.
First, let's look at the numbers (these statistics are taken from Jeremy GC's video, as was the inspiration for this post). In 2014, Riot announced that Leauge had 67 million players. Since then, they have not released new numbers. Now, if the game were growing, why wouldn't they? After all, it's good for investors, makes people want to jump in on the fun, and creates publicity. The reason is that the game is no longer growing. Not only has Riot not announced new numbers, but we know for a fact that esports vi has gone down, and recently, a figure in Chinese esports said that LoL had 64 million - a slight decrease. It is clear that at the very least, their growth has stagnated, if not stopped all together.
To diagnose this problem, let's look at how a game gets players - advertising, hooking the player in, and retention. In terms of advertising, esports is the big way LoL does this. However, now, it's not the only big shark in the ocean - other titans of the game industry are jumping in, especially blizzard, with HoTS, Hearthstone, and now Overwatch (which I'm hyped AF for). In other words, League has lost its status as the onl/one of the only big esports games along with Dota.
Hooking the player in is new player experience. As we all know... LoL's tutorial is complete shit. I bet if they spent a few months updating it and figuring out ways to better explain the meta, this negative trend will stop. The thing is, there are a limited amount of gamers who will put in the time to be in the "retention" category. And these players sometimes get bored, and eventually stop playing all together. Riot needs to reach out to the casual audience who aren't in this category in order to "make up" for the inevitable slow loss of the more dedicated audience, which is limited. Additionally,Riot NEEDS to make the ranked system become more easily accessed. Playing normals feels rather pointless and many players probably like the game but quit leveling from 1-30 which usually takes 300-400 games.
Now, retention. This is important once a player has seen/heard of the game (advertising), have been hooked/start playing for real (ranked.) This is also a big issue for riot. Let's face it - the recent changes have been... underwhelming. In an effort to make the higher ranks of the game more "shiny", when it's really the new player experience that needs touching up, Riot has alienated a lot of players (cough cough retcon still not finished cough cough. ) Not only do these changes fail to attract new players (they don't really care), but make older players quit. The other big problem with the retention of the game is that the ranked system is fucked. Dynamic queue has its pros and cons, but even before that, the community is toxic and it ALWAYS feels like you team drags you down. I don't know how to fix it, but Riot better now how to.