It won't pass.
If it does pass, it will immediately be challenged and stayed until it reaches the Supreme Court.
A Republican will be President by then and refuse to defend the case or it will be repealed.
Government can't make it prohibitive to buy guns, because 2nd Amendment was passed to make it so We the People could overthrow a tyrannical government.
Every Amendment in the Bill of Rights was put there to protect the states and We the People from the federal government. Constitution couldn't have been ratified without those protections.