Won't drop out

it would be interesting to ponder what would happen were trump to win, but that's not going to happen, especially not if his veep pick disavows him.

He through Trump under the bus last Monday in his debate so he could keep his hopes alive for 2020. I do not think Trump will drop out he is too afraid of being called a "Quitter"

after Trump drops out. This could be an issue, as the anti-Hillary independent voters unwilling to vote for Trump will have a candidate.

Although, to give your question the consideration it deserves, it might not matter. Let's say Pence decides he can no longer be the vice-presidential nominee on the Republican ticket. This has never happened before, but never mind that. I'd guess that the upper echelons of the Republican party would meet and pick a new VP, or maybe the Donald would flail around and find someone willing to join the ticket.

For one thing, early voting has already started. And we do not directly elect the President in this country. Too bad, in my opinion, but I'm not in charge of such things. In any case, the voters are selecting the electors who will sometime in December meet and cast their ballots. Then, and only then will the election be decided.

Were Pence to drop out, or if Trump were to drop out, the electors elected in their names (assuming at least one state votes Republican in that way) will vote for whomever the Republican party, in its infinite wisdom, has decided who the nominees will be.

And were either man to say, "Hey guys, I'm not longer running. Thanks for the honor, but I'm out of here." it would be a complete clusterfuck. Republican votes would drop off precipitously.