Mind the SNP's aim is to end the 1707 Union of Parliaments. Nothing to do with the monarchy and there would be little change there except she would revert to being Queen of Scots rather than our Queen as part of the UK. So as it was between 1603 and 1707 apart from the Cromwellian interlude. Saying that support for the monarchy is not as strong in Scotland as in England so should there ever be an indy Scotland then folks may well look at that sometime in the future.