I'd say MS is just going a different route. Console sales are not becoming less and less important for Sony and Nintendo.TBH that's likely a massive mistake to make. The reason why Microsoft is saying that they'll continue to support Xbox One consoles is that they will likely announce that Xbox One consoles will be able to play Scarlett games via XCloud. Yes it will cannibalise console sales of Scarlett, but it's increasingly clear that Console sales are becoming less and less important.
All it will take is the first next gen only game from a studio like GG or SSM to make the PS4 seem like an afterthought.