I talked to an Xbox rep at PAX about HTML5 support. Bascially, it's definitely going to be a thing, but expect a feature set like Internet Explorer. Also, no webGL or web audio, and it doesn't take full advantage of the console's performance.
I disagree with newt however about indies and consoles mixing in general - it's never been easier as an indie to get on console platforms - even Game Maker is supporting Playstation export.