I don't know, does the history of the guards actually matter that much to most tourists? Or is it just something cool to look at?. A lot of countries have similarly archaic rituals for the tourist doller (and I'd say even with the Royals the guards aren't really doing it for any other reason. My father actually did that at one point, apparently the enjoy getting to do something that gets instant public appreciation and has a more fun element to it that traditional soldier work). Plus, with the royals gone you'd be able to fully open up the palaces, there's got to be a lot of interesting stuff that the public never see.
Mind, there's a little bit of devil's advocate here. I do think the Queen is actually excellent at doing what she does (mainly by keeping her mouth shut, the big thing her children struggle with) and is a good ambassador for Britain. I think if anything's going to undo the monarchy it's going to be Charles kingship. Regardless of the fact a lot of idiots who think Diana pissed gold consider him Evil he enjoys sprouting off to much. He wants to be a different sort of King (even saying so with pretty much those words) and I don't think that's what the public, and certainly not the government, want. I think he'd actually have been much happier spending his life as a postman, now heading into retirement with an allotment to potter about in.
I don't actually mind Charlie so much, he's a lot smarter than often given credit (and was banging on about stuff like GM food years before anyone else) and certainly wasn't any worse than Diana in his hypocrisy during the marriage, I just don't think he'll be any good as a figurehead. Though if he's really getting on when EII goes perhaps simply letting William succeed would be the best bet?
Till the other one gets married, anyway.
[slanderous]Why would he stick photos of James Hewitt's mum in a lapdancer's bra?[/slanderous]