I can see Trump looking for possible replacements, but I can't see anyone who might be a help to him over keeping Pence accepting the position. After all, if Trump loses, they'd be made the scapegoat. If Trump wins, they get the thankless task of being Vice-President and it won't help them in future political endeavors.
There is a high chance Trump would either die (given his lifestyle and health) or become so senile even the GOP would want him replaced during his second term, so whoever becomes his VP will likely get to be president.
