It depends entirely on what Nintendo does. If they shoot for the core crowd with a serious attempt, we could see Microsoft jump ship to the 9th gen fairly early.
Personally, I don't see Microsoft making a 9th gen console. Their dev teams will likely shift toward Windows 10 development and eclipse the Xbox brand fairly soon. It really depends on how Windows 10 is adopted. If it takes off like expected, then why even support the Xbox brand with consoles anymore? I could see a shift to Xbox PCs at that point.
Hell, even Sony's future depends on what Nintendo does and whether it succeeds. If the next Nintendo console is more powerful than the 8th gen and can manage third party support, then Sony will be challenged to jump to the PS5 sooner than they'd like. If we're even going to get a PS5 that is; again, Sony could go the PSNow route and shift development that way to increase their install base dramatically. I doubt Sony going this way though, since PSNow has all but failed thus far and they'd have a much better profit margin on a dedicated gaming machine.
Like I said, Nintendo's next move determines the future here. Sony and MS are toying with VR, and Sony streaming/MS Windows integration, because they're both unsure of where they're going next, game-wise. They're just trying everything out trying to find the next big thing.
You should check out my YouTube channel, The Golden Bolt! I review all types of video games, both classic and modern, and I also give short flyover reviews of the free games each month on PlayStation Plus to tell you if they're worth downloading. After all, the games may be free, but your time is valuable!
