We won't really know the impact/extent of the realignment until after he's gone. Remember the GOP got shitcanned by the swingy groups in 2018, amd the thought was 2016 was an aberration amd sense would go back to the world, but it didn't turn out like that.

Trump brings out MILLIONS of voters who love him but don't care much for Republicans. How many of them stay loyal Republicans vs how many drift back into routine non-voters like happened with many of Perot's voters, depends on a lot of variables impossible to predict currently.