I think Insomniac, Bluepoint and perhaps Remedy are all likely candidates.
I don't want them to acquire anyone. But i'd be ok with is Insomniac because they pretty much only make PlayStation exclusives anyway, and bluepoint don't do much other than porting and remaking old games, 8/10 of their ports/remakes are also PlayStation exclusive. So acquiring either of these two wouldn't be so bad as it's not going to result in taking content away from other platforms.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)