75" plasmas are rumored for 2009. Of course they will probably cost a lot more than rear projection. But, I suspect they will be in the $5k range, 58" will be in the $2.5k range in 2009. They are building factories right and left.
The problem with rear projection is that it is hard to mark up a box of air a lot, so margins are getting crushed since everyone can buy the TI DLP chip.
LCD/Plasma are suffering too in small sizes. Manufacturers are abandoning the smaller sizes, constantly having to move up in size because margin disappears. At least with LCD/PLasma those first with the new factories that can build the large sizes have the advantage of lots of markup. This year plasma pretty much moves to 50"+ and LCD goes to 46"+ for the big manufacturers. Yeah they may have some models in the smaller sizes but they are consentrating on the larger ones for profit.