My big question about the XBOne, and by extension the PS4, is just how well they're going to support the "your only media center device" idea. They both sold the 360/PS3 as big on media center features, but local playback on both totally sucked. They each supported one or two basic containers, had no video player features beyond stop/start/pause/rewind, and just generally sucked for local or network playback. If you wanted to use them as a media box, you pretty much had to rely on a backend media server like Twonky/Plex/etc to do transcoding of everything, or re-encode your entire library to low quality big filesize crap.
It's 2013, Microsoft *OWNS* Windows Media Player and is putting a windows kernel in the XBOne. If this thing doesn't play every format and container right out of the box streamed from a network share on top of Netflix/Amazon/etc to put every Roku and WDTV to shame, frankly they're doing it wrong. A media center is more than just a device that can halfassedly stream Netflix and Hulu.
My Receiver is full up, and so is my TV stand. Microsoft and Sony aren't just trying to win real estate this time, they need to be giving me a compelling reason to be *replacing* the other devices that are already there.