He already has been for years. See the Black Spider memos he secretly sent to ministers, and all the secret carve-outs the Queen had. They have their grubby fingers in politics, but are just clever at hiding it.

Not necessarily the end of the monarchy. Parliament would just choose a new monarch as it did in 1688 when Charles II tried to choose an heir that Parliament didn't like.

It's been settled via the civil war and the Glorious Revolution, power in the UK rest ultimately in the House of Commons not the monarchy.