"What can Riot do to save League!?"

I actually see this a stupid amount on these boards. Someone with a fix-all solution or "Five easy steps to get players playing like it's 2012". Here's the actual dealio.

Short answer is: Nothing.

Long answer:

League, and the MoBA genre as a whole, have hit their peak and have plateau'd. By comparison: DOTA2 just crossed 13 million unique players in the last month. Their exponential growth is done. Average players are stabilized/on the decline as well. (Accoridng to Steamcharts. It's not 100% accurate but it's a good enough indicator) League, which is still among the most played games in the world, likely has less overall players than it's peak. If I had to guess, my most generous estimate is around 60 million unique logins per month while most damning would be around 50 million. (We don't know facts but I'm guessing somewhere between 60 and 50)

Already we see the genre that's overtaking Mobas: Hero shooter. Overwatch, Battleborn, etc. Everyone is scrambling to get on this gravy train. Will it uterrly kill the MoBA? No, no it's just going to take some players. We are, however, going to see a massive surge of these types of games. We already see it with things like Lawbreakers, Quake: Champions and otherwise. Why go into an already saturated MoBA market when you have this fresh market you can try to be one of the big 2/3/4 in? Anyone trying to compete with league/dota/smite/hots at this point is digging their own grave.

Does this mean league (and by extent other mobas) are kill? Of course not. They'll still hold onto a dedicated playerbase and do well enough. Hell, I'd guess that League is still gonna be really high up there, maybe even #1, for at least two more years. However, there's nothing Riot (or any company) can do to boost their game back to where it was in the prime of the game. Yes, they can do things to attract new players or entice people to come back for a short time. We see it with champ releases, rotating game modes, etc. The alpha client's release will likely provoke a small surge or returning and/or new players. However, there's no "fix all" solution. Solo queue coming back won't magically fix all the problems, nor will completely removing runes make the game the most played.

The game still has plenty of life in it and no, we're not going to see this game closing it's doors for at LEAST another five-to-seven years. (For reference/comparison: WoW started in 2004 and hit it's peak in 2008/2009. Meanwhile they're still around in 2017. WoW's peak was 12 million or so. League gets to chew through around 60 million) All that said, there's nothing you can do but triage the situation. No amount of boasting importance or providing a singular "Fix this and everyone will come back!" will make people return.