Which 3 companies? MS, Sony, Nintendo? Or you include Roblox or EA or…?
~100 years ago there were ~200 car companies. And then there were 3. Now there are maybe 3 dozen of some size. Industries start with an explosion, then the winning formulae rise to the top and hoover up the rest that haven't closed down, and then it depends.
If the investment level for progress is huge—eg large aircraft or computing chips—then the big companies usually hang onto the market. With smaller barriers to entry, new companies can arise and get decent market share. Gaming is in this category—eg the rise of very recent growth of Roblox and Epic.
So long-term I don't see the industry owned by a few. There will always be the top players, but plenty of other significant players also—eg car industry is dominated by Toyota and Volkswagen, but there are plenty of other significant players like Ford, GM, Daimler, BMW etc etc. And then there's the very recent rise into the stratosphere of Tesla—who knows where that one will lead.
My personal belief is that in mainstream gaming, there will
only be 2-3 game companies that own everything. And I'll tell you why. Back in the early days of gaming, a company could come out with a high budget, blockbuster every once in a while, and then fill in the gaps with smaller games. Back then, we just expected the average game to be one of those smaller ones, and we'd get a really big game here and there. But then sometime a decade or so ago, they started putting out more big budget games, and less smaller ones. They trained us gamers to expect that more, and it got to the point to where now every single game
has to be a big budget game, and if it's not, it's going to fail.
Having a bunch of game companies out there, all trying to do that all the time, isn't going to succeed. So the ones that can't hack it are getting bought out by the ones who can. Eventually, you end up with 2-3 huge game companies gobbling up all the rest. It's just like Walmart and Amazon killing off all of the Mom-n-Pop stores.
The only thing that will be left other than that will be the indies that don't give a rip about the gaming world machine, and they just want to make games because they still have a vision for making good games.