At a Convention for Proposing Amendments under Article V, the 2nd Amendment will only be repealed if two-thirds of the States Assembled in Convention approve such an amendment
and if the legislatures (or ratifying conventions) of three-quarters of the Several States ratify such an amendment.
You have nothing to worry about. All it takes is 13 states to say No at ratification time, and any proposed amendment is dead.
Trust the Framers.