Indie games will just grow and grow. Look at DOS2. There is also a chance that some talented indie team will destroy some huge budget mainstream bloated dev team in sales. It has happened before and it will happen again, and it changes the future of gaming. So say DOS3 is even bigger again and their team grows even more. Meanwhile people start getting bored of the mass produced Fallout and Elder Scrolls games that have no innovation. By DOS4 and Elder Scrolls 8, they both start competing for sales and DOS wins, and yet it will be made with one tenth of the budget. More private investors and publishers start to question the huge budget, dumb mainstream philosophy and bigger budgets will start going to indie devs who make real games for real gamers and have a higher return on investment.
And even without any big wins like that, it will happen anyway. There will always be many millions of plebs just waiting for the next GTA, CoD, Elder Scrolls, Mass Effect, etc. But the top end mainstream games are an arms race. The budgets grow more and more enormous. You can't make one of those games would spending huge amounts on music score, professional voice actors, super high end graphics engine and graphics assets, and it has to be a big game too, and then it needs tens of millions to be spent on all the full screen ads for every gaming website and all the paid for reviews. It makes money in the end but the costs are huge. Meanwhile some small team makes an indie gem that catches on like Minecrap and makes 2 billion dollars for a team of 3 people working from home.
The gaming audience is just so big now. Niche indie games don't need to serve a small audience anymore. With some luck and word of mouth they can be huge.