Donald Trump doesn't care one way or the other about abortion. I doubt he'll give the issue any weight whatsoever in regards to choosing his running mate.
Actually, Donald did at least flirt with the idea of a ban... asking what would happen to the women if it were banned. Being a dealer has some virtues - it means not taking the option off the table.
Trump may not care about abortion per se, but he cares about winning, and he seems to have got the message that he needs pro-life voters to win this election. I doubt he'll choose a pro-choice running mate.