>Tesla has finally alleviated the "cross-country road trip" problem in a way that superchargers really couldn't.

As someone who's taken a one-way cross-country trip before (NYC->SF), no, no they haven't. The system only works if it's round trip.

Gas powered vehicles continue to be more practical unless you are firmly confined to a 100 mile radius in your vehicular needs and can afford to supplement your electric with an extra vehicle (the case for all Tesla owners so far) and/or alternate modes of transport.