The only benefit I can really think of comes with streaming, with 1000 people playing the same match potentially resulting in a very strong following in the case of epic matches. But I'm really struggling to see any situation where a large population results in a meaningfully different game that isn't chaos.
I think the benefit is quite large, considering the streaming audience can spot the ingame Ads with more attention while watching
But more than this, this attention can also be used to limit the chaos. Players knowing being watched might be after reputation. Reputation could even be the currency for upgrades. So causing chaos -> worse guns, less badges on your skin.
In a RTS > FPS scenario, the less reputated players will also get a worse start position ending up as cannon fodder, while the good guys get the cool missions like stealing the flag.
I think it can work if the chaos guys are already taken into account in game design, and they can be jerks on purpose - still having fun and value for the game.
Actually BR is already an example for this. When i played Quake3 Clan game mode (team last man standing), i wondered: Would this be fun with no players? No - too much waiting time after death.
But now with BR the same thing is very successful. It even is a 'new genre', and new genres is what we need the most, and what we should expect form new technology. New genres could even help with further growth to prevent my pessimistic prediction of a downfall in gaming industry.
I think streaming is one indication of an upcoming downfall. It did not work so well for the music business. Just moving existing games to the new platform will only weaken the industry - we need to give those platforms new kinds of games, not just an easy way to play them.
I suppose a 1000 player Tomorrow Children type thing might be interesting, except you then have the problem with each player wondering about their value to the game.
I don't know TTC, but if we take Minecraft as an example, or one step further - a similar game where the players are also the content creators, then we have the final single remaining game we likely are all heading to.
Think of a game where players create their own minigames like in Dreams but in a consistent large world like Minecraft with consistent physics and ecology. They will also form larger communities to create larger games / experiences / whatever. There are always enough good level designers / artists / script coders within a large community.
Again reputation could be used as a currency to keep the whole thing working, together with laws of physics, finite transformable resources as in Minecraft, or whatever else. I fdone right, the game would work without any scripted missions, without telling the players what to do, without never ending afford to add new content to the game because the users do it better than we could do.
Now i don't know if i want all this to happen, but it will. At first there is a lot of work for us to do to get there, but at some point we will be no longer needed?
You may think: 'No - users can't do this, they'll just create mediocre experiences and chaos', but i doubt it because the best games are (or were) those with user generated content.