Are you asking about NYC real property taxes for FY 2013 or the 3.8% federal income tax on capital gains above the exempt ($250K single 500K married) primary residence exemption for taxpayer's with incomes above $200K single $250K married?
In either case, I agree with William. Most people buy and sell due to their own life circumstances rather than tax considerations.
What property tax laws are you referring to? If you're referring to the possibility that the mortgage interest deduction might be limited or discontinued this has happened yet and I doubt that it will. Even if it does it's actually a minimal deduction for most people. Having sold over a thousand homes in my career to date, I've never once heard a single buyer mention this as a reason for buying a home.