Microsoft has lowered the price already last month. The price decrease required Microsoft to take a $900 million hit on the books. To lower the price again would require an additional hit, I don't think they will be doing that anytime soon. BTW, MS did not write off $900 million in Surface inventory, they had to reduce the amount they were keeping on the books in the value of the current Surface inventory. If they were planning on selling the 32 GB RT for $450 and now the price is $350 they have to account for that change.
The bigger problem is that they must be sitting on a boat load of inventory to have the price change require that bit of hit on the books. We were at two MS conference this summer where they sold 64 GB RTs with the touch keyboard for $99. I was actually surprised they did not give away RTs to all the attendees at build conference. I know they gave them Surface Pros & Acers, but why not also give the developers RTs to try and spur development.