The GOP won't have the face of Trump in office, come 2021. They will have DeSantis in office who would be the frontrunner for the GOP nomination come 2024; however, Dems have maintained a lead in the popular vote, since 2000 and it would be very hard for the GOP to match that, without, somehow getting in, like Trump, on a technicality with the EC college, they have lost the popular vote 4/5 elections.
2016 was probably an abberation in the gap between PV/EC, because presidential campaigns usually don't try to campaign in "safe" states, like the Clinton campaign in California or Illinois. I don't think the GOP can count on a permanent electoral college advantage (that's crazy-talk lol).