Not even close. Seriously, anyone who thinks this is even remotely true really needs to step back from the AAA Scene for a moment.
In terms of sheer game mechanics, we're limited in what we can sell to an audience in terms of "new" experiences, because if it's new then audiences won't know if it's good or bad and if they like it, and thus will shy on the side of caution. It's why new I.P.s sell worse than sequels - not because they're bad, but because, frankly, no one knows if it's any good the first time around. No one knew what a survival horror game was when they first came out, but once you pull it off, you've got an entire genre to yourself.
This fact really limits us creatively because we have to begin game pitches with "It's like Halo but..." or "It's like GTA but..." in order to get funding for a prototype that we can then use to demonstrate the game, and then get green lit for full development.
That is, unless the Publisher asks for a vertical slice - which a lot still do - in which case the game has to be stripped back to be simple enough from a design point of view that building out an entire level with every game mechanic complete is relatively cheap, otherwise it won't get funding at all.
If you're skipping the Publisher model entirely, than your ideas boil down to what you can afford to do. You might personally have the greatest open world game that will ever be made fully designed in your head - but you don't have the US$60,000,000.00 needed to make it. So, retro games, small mobile titles, or niche genres with simplistic assets are the best you can cough out.
As computing power becomes a non-issue - and we're pretty close to that point, actually - game development itself will open up to the masses. That's where you're going to see the magic happen. A million people will a million new ideas dropping the next Minecraft onto the internet every six months.
Then... the industry will loop around again. We'll grow tired of the never ending cascade of small indie titles that will flood and drown the gaming population. You'll be so tired of yet ANOTHER new genre mash up, that we'll long for a really, really, really well made, high quality and expensive game experience. And we'll slowly move back to the AAA model again, only with the new developers that are getting on their feet today.
No, we haven't even seen the best ideas, let alone ALL of the ideas. Not even close.