TBH I don't think flip flopping to the mainstream opinions of the national party is that meaningful.
Presidents are always going to do whatever is popular with their partisan base. Sure Romney was apparently a moderate in the 90s, but he would have governed as a very conservative president.
Gillibrand's past as a Blue Dog is electorally useful, but it's really not going to matter too much if she is elected, because the pressure will be to enact progressive policies, which she would.
Sure but Romney never made it to the presidency because he was seen as insincere. The same curse that decked Al Gore and John Kerry. And they were men.
Romney being seen as a plutocrat that didn't give a damn about regular people was what sunk him, not flip flops.
Trump has flipped & flopped more than any other person in history and no one really cares. Why would that matter for Romney?