England as a republic? I cannot imagine such a thing. Will all of the countries that make up the United Kingdom also become republics or would they decide to remain constitutional monarchies?
If the British monarchy no longer exists then Commonwealth countries like Canada, Australia and New Zealand would all have to become republics, with, horror of horrors, elected presidents and state governors.
Australia would have to rewrite our constitution to be more like India, Ireland and South Africa. It could work but does the Australian populace want this? I'm pretty sure that I do not. The turmoil would be horrendous.