Vance sees kissing Trumps ass as the easiest way to be on the ticket for Fuhrer next election cycle. If Trump wins or loses he won't be in physical/mental shape for the next election and Vance sees sticking his nose intestine deep up Trump's ass and using the next 4 years as his sounding board to say whatever smoothbrained maga wants to get his name out there.
I think this was Pence's play too. He just had a moment of clarity when we saw a glimpse of his future where the word "Pence" replaced "Benedict Arnold" as the default word for "traitor" and didn't want that to be his legacy. As much as I dislike Pence, I respect him for his moment of authenticity to certify the election in the face of fascism .
This line of thinking assumes Trump is capable of concocting elaborate schemes to hide his intentions. I don't think he's that intelligent and I don't think he tries to hide his intentions at all. He's exactly as dumb as he appears and his intentions are plain. His style only works because the people who support him are also idiots.