In the tax reform lit it is usually presumed that housing will always get some kind of concession for political reasons. I do not think this stems from the biases of the tax wonks, who would be happy to get rid of most any ill-conceived deduction, including those for mortgage interest and property tax. It is true that it is one of the most expensive and regressive (e.g., most benefits go to higher-income families) in the personal tax, but the regressivity is a bit (not completely) illusionary since it follows from a static point in time. Properly speaking, the tax benefit is received by all who will purchase, are purchasing, or have paid for a house. From a lifetime standpoint it is spread much more broadly than if one limits one's view to those paying a mortgage at a given point in time. It's still regressive in the broader view, but not as much, if that means anything.
My main point is that politically there are many riper targets. If anyone wants a shopping list, just download the 'Analytical Perspectives' volume of the budget; it contains a list of tax expenditures in the personal and corporate tax codes, including their annual cost. Or read Citizens for Tax Justice report on "tax entitlements," also free on the web.
mbs