Well I'm sure the French will be pretty pissed but really what can they do? Their King is dead, most of the leading nobles are probably dead or captured and their army is defeated. And historically nation's under a Regency don't go to war. That's not to say that Francis II won't be gunning for vengeance or anything, but it will be some years before that happens.
Oddly enough, they seem to have bounced back from OTL Pavia enough to fight another war with the Empire.
And then another.
And then another.
And--look, I could keep putting 'anothers' for some time. France has emotional reasons to go to war again. And, believe it or not, it has practical ones--letting Charles V&I turn everything on both sides of them into 'Habsburgland' is not good policy. And so, Regency or no, war is probably likelier than you think.
POSTSCRIPT--Actually, let's remember who our Regent in this scenario is. Louise of Savoy. A woman whose devotion to her son arguably bordered on the obsessive. And the possessor of every mental and spiritual virtue her son had, as well as quite a few he rather wished he did.
If it's at all possible, she's avenging her baby boy. And if it isn't, she's going to give it a try.