Of course not. Not in 2016 and not ever.
This question has been asked over and over again about the party not in power and somehow, they overcome the "odds" and win the Presidency at some point.
Except the Whigs and the Federalists
I am talking about modern times, obviously. The Republicans hold the House and the Senate and most state gubernatorial mansions and legislatures. This can't win meme is overblown.
My view is that we don't know. I think that if the Republicans continue on the path of Trump, there is a decent chance they do turn themselves into a rump regional party that is essentially irrelevant in presidential elections. If they change course, I think there is a clear path back to national viability.
For the record, I hope the Republican party does recover at some point. Having a coherent debate over real issues is important and we are being disadvantaged as a nation if we don't have those meaningful debates.