The market seems to be changing towards a more mobile-oriented, pick-up-and-play approach. The way things are going, the next Xbox could be their last, or at the very least, the last home console from Microsoft as we know it. (By that I mean that my prediction would be that if the next home console from Microsoft doesn't result in MS dropping out of the console manufacturing business, then the only way I imagine them staying in would be because of some very large, impactful changes to the experience.) I suppose the same could be said for Sony as well, but I think that if Xbox folded their hand, and allowed Sony to absorb most of their players, it would allow Sony to thrive in the smaller, home console market.
I'm hesitant to submit this because I mean no ill will. Let me make this part clear: I don't desire to see Microsoft drop out of the home console market. Rather, if I had to predict what's going to happen, with my limited knowledge, and garbage track record, this was my prediction.
Also, Microsoft has deep pockets, and I don't see them disappearing entirely, but I can see them switching exclusively to a games as a service model and dropping the hardware that comes along with it in lieu of something like Stadia. I can see Sony doing the same, and not due to suffering sales, but rather just because that's the direction the market is headed.