Rates are heading up. So the answer to your first question is easy. They could even be higher by the time I'm done making this post. Projecting too far into the future I have little interest in. Were I to speculate on numbers in the future, I'd select lottery numbers first. Forced to speculate further, I'd imagine the rates are as low now as they're going to be fore some time.
As for putting more downward pressure on home prices, that's an interesting question. The market is off, by most pundit's estimations, by as much as 30% from the high of mid 2006. So it's losing 7+% per year. How much more could it really lose? Many sellers have lost whatever equity they made during the boom years b/t 2002 and 2006. These sellers are already selling at a loss in many situations. Futher, a considerable number of them were first time buyers, who are already in their home a bit longer than they had expected to be.
Can you put downward pressure, then, on someone who can't afford to get out from underneath a mortgage they're upside down on? I don't know. I'm sure given the opportunity to lose their savings or not sell their home, many people will eventually choose to not sell their home.
There is no crystal ball with which to know for sure. I can tell you this...You'd rather be in a new home, assuming that's something finacially within your power to do, now, while the prices are great and the money borrows cheaply, than wait until the perceived best deal to ever come down the pike materializes. The savings won't be as much as you think they will be, and if you wait too long, you're going to hate yourself for not buying what you want over a small monthly payment difference. Settling for what you don't want is never a good reason to buy anything.