Lowering the interest rate will not help. The last two hikes caused exactly a one day bump up in stock then a massive sell off. You can go to zero but you cannot help people pay off debts that are more than the value of the property they are paying off. They are better off to walk even if the interest rate PAID YOU 3 - 4%...
This is all going to depend upon your personal point of view.
For appraisers, the credit crunch is a very big factor in their practices. A large part of that credit crunch revolves around the resets of adjustable mortgage rates.
IF the fed moves fast enough and strongly enough (and I am not suggesting they will- so this is only an "if"), it could easily modify or even totally cancel the new higher payment requirements for some- perhaps many.
Should that happen, fewer homes go into foreclosure thereby easing the inventory levels. Further, lower rates will improve overall affordability and that could spur sales somewhat for both new and existing homes. In addition, there will be those who will opt to refinance, adding to appraisal volume.
Always look at the whole picture. What I 0outlined above may well not come to pass, but it does blend into the logic of economics.