The basic notion that Trump has an Electoral College advantage seems right, he obviously did in 2016, but I'm pretty skeptical that we can say much right now about whether it will be larger, smaller or nonexistent in 2020.

History would say you should have a loose prior toward it being smaller since the Electoral College advantage is historically not very durable, e.g. it benefited Democrats as recently as 2012.

If you measure electoral college bias by comparing the vote shares in the electoral college tipping point state against those nationwide, the last 3 presidential elections with a Republican EC bias were 2016, 2000, and I think 1992. Had the numbers written down somewhere...

2016: Wisconsin, R+0.77% USA, D+2.10% bias, R+2.87% 2012: Colorado, D+5.37% USA, D+3.86% bias, D+1.51% 2008: Iowa, D+9.53% USA, D+7.27% bias, D+2.26% 2004: Ohio, R+2.11% USA, R+2.46% bias, D+0.35% 2000: Florida, R+0.01% USA, D+0.52% bias, R+0.53%

1996: Pennsylvania, D+9.20% USA, D+8.52% bias, D+0.68% 1992: Tennessee, D+4.65% USA, D+5.56% bias, R+0.91% 1988: Michigan, R+7.90% USA, R+7.73% bias, R+0.17% 1984: Michigan, R+18.99% USA, R+18.22% bias, R+0.77%

1980: Illinois, R+7.93% USA, R+9.74% bias, D+1.81% 1976: Wisconsin, D+1.68% USA, D+2.06% bias, R+0.38% 1972: tie: Ohio, R+21.56% Maine, R+22.98% USA: R+23.15% bias, D+0.88%