I think others have made a good point concerning the fact that Microsoft mostly seems concerned with phones/tablets. Quite frankly, it's safer to invest in that than to risk developing a handheld that'll run the course of the PS Vita (though I blame that on Sony being stupid more than anything else).
Now, to be clear, Nintendo
is thinking about developing apps on mobile devices, but (at the moment, at least) not games (
http://www.theverge.com/2014/1/29/5359472/nintendo-investor-briefing-q3-2013).
I would like to think that if Sony could support it's handhelds properly, that they could win back a bit of the handheld market. The actual PS Vita system isn't bad, but it lacks a proper game library (though frankly, I think the same about the 3DS), and perhaps worse than that, promises were made about implemented features that never really were fulfilled. Plus, it was significantly more expensive to get into, thanks to the special memory cards and generally higher price of the system.
I think, ultimately, one of the worst aspects was that they decided to trade off battery life for hardware quality. Battery life and game libraries are, perhaps, the most important aspects that any handheld must have. The Nomad, Game Gear, Lynx, etc. all made this tradeoff, and obviously history tells us the rest. xD Not that this is the only factor, but it remains a very important one.
Not to say that the PS Vita doesn't have good games. But I hardly recognize any of the names, and those that are usually available in the store just don't look very appealing for the price. That, or the ones that DO look good are available on a console, and I kinda hate not to buy the console version instead, since I get a better looking (and sometimes, functioning) experience for the same price or less.
Sorry to go on a Vita rant. xD I really like the system and what it is capable of. Same with the 3DS. But I'm having a hard time finding much of interest for either console like I've been able to with the PSP. There's never much available in store for either system, and aside from a few titles (like Danganronpa), there just isn't much that's...
interesting there. It kinda feels like the game libraries have taken a step back since the last generation of handhelds...