If Princess Caroline became ruler of Monaco, would she retain her current style of HRH or would she revert back to HSH?

Her Serene Highness, Sovereign Princess of Monaco - the title /style would be that which she would hold in her own right - not the HRH which was acquired by marriage.

It is an alternative to HRH and not inferior to it (it was scrapped in Britain by George V) - in French the title actually translates as Her Most Serene Highness.

Interesting, a rise in power and a drop in the style with which she is addressed. I know of nothing that would prevent her from using both. HSH Princess Caroline of Monaco, HRH Princess Caroline of Wherever. The HRH title is only a courtesy title though, as Germany is now a republic and the Royal houses are no longer recognised. One just has to look at the Duchess of Alba's immense and very impressive array of titles to see that there is no reason why it could not be done. Queen Elizabeth is Duke of Normandy, a title that I doubt the French will ever recognize, cheese eating surrender etc etc..

She would have gone back to being Her Serene Highness. She would have used the Royal House Name and surname of Grimaldi as well.

I shall have a lucky guess, dear retnavybrat. I believe we will not know the answer until that event becomes a likely reality. I understand that She may actually be entitled to have a choice of which style to take.

I'll wager She would do well to buy Herself a chic organic farm if prestige is what She craves.