What happens with Jared and a dying monarch?
We probably have to wait until the Rulings under the card in Gatherer, but this seems to be a case where one of Magic's Golden Rules applies:

101.2. When a rule or effect allows or directs something to happen, and another effect states that it can’t happen, the “can’t” effect takes precedence.

The game doesn't require that some player is the monarch (it even begins that way) so for the moment there will be no monarch.