their last chance to hold on to power

The nature of the 2 party system means there will be a Democrat President again someday. That could be as soon as 2029, but almost definitely no later than 2033 or 2037. The next Democrat President opens the borders again on day 1, and also reverses all of Trump's executive orders, and pardons anyone Trump prosecuted.

A new President usually also wins in Congress, which means the new Democrat President will likely have a majority in the House and Senate, like Biden did for his first two years. They can eliminate the filibuster and pack the Supreme Court or pass whatever law they want.