I'm with Scott and Robert on this
I think the positive result of discouraging excessive borrowing on equity--a bad trend lately--overrides any negative effect on house purchases.
I don't know anyone who decided to buy a house just because they wanted the deduction as a primary reason. Sure, it's icing on the cake, but that's about it.
Again, I don't know if there was any negative effect on car sales from eliminating interest deductions, but I don't remember one.
