None of the reasons that the current passenger rail system in the US is horrendous are technical. It's entirely feasible to build proper passenger rail networks with current, look at Japan and western Europe for some examples. The problems are all sociological in nature.
You can plasma sheaf the train head. The stability of wheels/rails and other mechanical stuff at say 700km/hour is probably a bigger issue than air resistance.
Nobody has tested maglev at 700km/h. https://en.wikipedia.org/wiki/Railway_speed_record The conventional train speed record is only 30km/h slower than maglev. The issue with the conventional train wasn't wheels it was the overhead wire contact (though at that speed maglev is more efficient)
