When will HD be ubiquitous? Well, as long as possible by the looks of this. 

If you're wondering why Microsoft and Sony are going to drag this current generation of consoles out for as long as possible, look no further than this:

Over half the users who played Gears of War 2 so far do not have HDTVs…My point is, of the systems that are out there now, the majority of them aren't plugged into HDTVs. So there's no way we're ready for the PlayStation 4 or the Xbox Whatever.
This is almost the same as saying that more than three quarters of people surfing the web use Internet Explorer and a huge number are still using IE 6. Sad, but true.  [Eurogamer via Kotaku]