Honestly, the Mortgage deduction is a regressive giveaway to people who are big spenders on housing and helps contribute to housing being less affordable in the US than it could be.
It really isn't "fair" for renters and people with modest homes (sub $200K) to subsidize higher income people with up to $1,000,000 of mortgage debt (and the higher their tax bracket, the more value it has in subsidizing them).
Please take regional differences into account. In the NY metro area where I live, sub $200K gets you, at most, a one bedroom apartment, 825 square feet, near the highway and in poor shape. Why live here? Well, family, friends, and jobs.
I've been trying to think through what will happen if homeowners lose the property tax and mortgage interest deduction. It seems to me that this will throw local governments in areas with high housing costs into crisis, property values will crash, and not just for homeowners but for landlords too. So this may be good if you are looking to enter a market, but bad if you already own. It may be a time for (large) landlords like Trump, with extra cash, to snap up bargains.
Eventually, once homeowners who are not able to afford their homes without the deductions have sold and left, property values will stabilize again, but since there are so many people eager to live in areas within a livable commute of the big cities, I am not sure whether the prices will go down significantly.
Personally, I am concerned that this will be damaging to my community, which is a working-class suburb struggling to retain its nature in the face of development. I expect that many families will have to sell to investors, who will knock down the single-family homes and build rental units. However, with falling property taxes, services including schools will decrease in quality. Ultimately, this will become a less desirable place to live, since if you want to live in an apartment near the city, with access to mediocre schools, there are many better options... and landlords will find themselves with empty units.