Even if Trump gives on some gun control issues at the margin, he'll still get the right to vote for him. Whadda ya gonna do? vote for Harris/Biden/Booker/Warren et al because he bailed a bit on you? I think not.
Unless we get a viable third-party candidate. That would be a game changer in an election where Trump is wounded from trade war / 2A issues and the left nominates a non-Biden.