Since there really is no standard set for HDTV
The standards for HDTV have been set for a couple of years now. The ATSC (Advanced Television Standards Committee) has published the specification. Nothing is going to change in regards to modulation format, resolution or compatibility. its done
Also, 480P is not the equivilent to 1080i
Both 720p and 1080i are "real" HDTV. When you get the chance, check out HBO HD and then switch back to a DVD you'll notice a big difference. The debates of 1080i vs. 720p are endless, and go on for months over on the avsforum.
The limitation of only 480p on a 42" screen its not quite as big of a deal as it would be on a 120" screen, but there is a difference nonetheless. For an extra $400 Panasonic makes a pretty good 480p 42" panel which looks pretty close to its 720p sibling.