I dont think exporting to XBOX is going to be difficult because now Microsoft has come up with a Universal App concept. So any app you develop for Windows 8 or Windows Phone... will also work on XBOXOne.
I agree. Most likely you will see support for Xbox One once they open the floodgates to everyone(not just the ID program). Even the BUILD demo showed how you can use the same Visual Studio that Windows 8.1/Windows Phone 8.1 uses to create a universal app. Sony on the other hand, hasn't made any mention of supporting HTML5. So I would bank on Xbox One this year or next but not Sony. Don't forget the Wii U is a huge opportunity as well, I'm having good success with it.
-Mike