AFAIK, there are already no 720p displays currently in active production.
720p is defined by the ATSC (and is broadcast at) 1280 x 720 pixels.
Tell me what displays currently being produced are 1280 x 720 pixels?
Not 1024 x 768, or 1024 x 1080 or 1280 x 1080--these are not 720p displays.
Not 1366 x 768--these are significantly higher resolution than a 720p display, although it's better to think of them as 1080p displays that have been "down-rezzed" to reduce cost.
As far as content--yes, 720p is losing market share. There are only a few 720p networks now (FOX, ABC, ESPN l/ll, National Geographic) and no new ones coming on line--virtually all announced new HD programming is 1080i and, Hi-Def discs are 1080p.
Through the use of digital scaling, a display of any resolution will always be able to display a 720p or 1080i/p signal, but scaling often softens the picture and adds digital artifacts.
The bottom line is, it won't be too long before all HD displays are 1080p and the overwhelming majority of HD content is encoded at 1920 x 1080.