I sometimes question Microsoft's true dedication to the Xbox brand. The only reason is because Xbox is NOT remotely their bread and butter. Windows is their main source of income by far, though I hear now cloud computing is becoming their thing more and more. With Phil Spencer's efforts sure gives the platform more credibility, but they are contrasted a bit from the other companies.
Nintendo is easy. They are only about games. Yes there are Amiibo and a theme park etc, but at it's core they are a video game company even if they is now extending to smartphones in some capacity. They live and die by video games by and large so you know their commitment is real even if many gamers have tragically abandoned them. Their heart and soul is video games.
Sony is more difficult. They reluctantly entered the video game market, but caught fire immediately and now it is their greatest tent pole. Their company has hemorrhaged money in sections of it's business except the Playstation brand. They are going to give it their everything to nurse that money stream for sure.
Microsoft could leave the video game market tomorrow and they would be fine. I am quite confident they wouldn't miss a beat. That being said, I would find it sad to see them go. I do believe in many ways they keep Sony honest and innovating, not to mention pushing hardware forward.
If there is to be a new machine so soon from Sony, Microsoft would be wise to definitely release their next iteration AFTER, preferably soon after, Sony releases theirs. If Microsoft is serious in competing with Sony, then they should wait and let Sony weather and backlash from consumers upset with a new machine so soon. Second, in doing so they can release a new machine conscious free because, hey, after all Sony has already done it. Third and the BIGGEST reason is after all the abuse the XB1 took over being underpowered, MAKE THE NEW XBOX MORE POWERFUL!!!!! It may not save Microsoft because it didn't help with the PS2/Xbox original battle, but they were an upstart with no presence, things MIGHT be different, but at least Xbox wouldn't be the whipping boy any more.
Nintendo's new machine needs to best the PS4, not so much the PS4.5, but if it comes out under PS4 without a life saving gimmick, then Nintendo will continue in the legacy of Gamecube/WiiU, great 1st party games, but no sales. This coming from a Nintendo man at heart.