We're all assuming that Charles II has a son in this thread. But what problems would arise if he only had, say, 2 daughters?
We're going with sons here. Also it would be 4 daughters. All of Catherine of Braganza's pregnancies went threw here. And the only thing that would change is the gender of the monarch. I mean the royal House's name would eventually change when the Queen's child became Monarch but other than that.... nothing I can think of. Though it would be interesting to see who becomes the Queen's consort.