Just like Bush was supposedly the last one for a generation because of the emergence of the unstoppable Obama coalition? The fact that Trump won, even with his unpopularity, shows that if Republicans nominate someone less toxic to large swaths of the public, they can still win (even a majority of the popular vote).
Bush was not wrong (so far). Trump is not really a Republican. He's really more of an independent who is Republican in name only (and only because that's the only way he would've been elected, by running in one of the two party's primaries). He is authoritarian, and a dictator-wannabe; there is barely anything Republican (much less patriotic) about him.