Obama will certainly take North Carolina, probably by 25 points. I suspect he will win Indiana as well, although it will be close. After May 6 (NC/IN) the Democratic race will be over. If it keeps going, Clinton will win WV and KY in landslides, and Obama will win Oregon by 15 or so points.
The Republicans would unquestionably prefer to face Hillary; no contest whatsoever there.
I think the Democrats will certainly win in the second case.
I do not think Hillary would win in the first case, because Obama would be insane (imo) to be her VP; and turnout among D-sympathizing 18-29’s, as well as blacks, would crash. Basically it would be a rerun of 2000 — the same old heuristics bandied about, the same trench warfare, and the same low turnout.
An Obama nomination will probably commence mark the end of Nevada, Virginia, and Colorado as Republican bastions, whereas very gray PA would move decisively into the Republican column. Tennessee and North Carolina will become permanently more competitive.
Increasingly, “GOP” stands for “Gray Old Party,” sadly.