I really don't think Trump makes it through four years of a presidency without suffering mental or physical issues. 

He has a family history of Alzheimer's, is already showing serious cognitive decline, and his diet and physical health is extremely poor. Not to mention he will likely be both a domestic and international target for assassination (which is sad to say because I don't condone violence to anyone, but this still remains true and needs to be said).

For many reasons, I don't think Trump would be able to serve a full term.

And, I've always felt that Peter Thiel, Opus Dei, and others have bigger plans than Trump and hope to make Vance president if Trump were elected. They will jump at any chance to remove him if possible.

Vance is more than only a traditional VP, he is probably the next president unless Kamala Harris wins the election.