A few answers to your questions...

its funny that anyone would think that these features are considered luxury class...IPA maybe but the rest is more safety than convenience. also most are ones that current Prius owner have asked for and have advised they would also be willing to pay for them.

heated adjustable seats, sunroofs? sure they add cost, but Toyota has also taken steps to reduce costs in other areas. major revamps of existing model years has happened frequently, major price increases have not. so i see only an incremental increase in the 2010 Prius based more on inflation than anything else.

now will the downturn affect the price? i dont think so. dealer incentives will though since they can be added and removed at any time, so as the economy recovers the price goes up as the incentives get smaller