There are some things I think HM does right, such as keeping the hated "stiff upper lip" and generally not letting it all hang out in terms of letting us all in on her innermost thoughts and emotions and dreams and ideas and opinions.... ad nauseam. She holds the monarchy to be above, or to transcend, these things. She takes her duty, as far as the monarchy has a "duty" these days -such as bestowing honors, taking part in ceremonies, supporting various charities, etc., very seriously, and goes about them day in and day out, year in and year out, without drama, and generally without telling us all about it. A simple photograph or two suffices. In my book, these things are what separate the Royal Family from "celebrities".
However, she has made many misjudgements over the years -off the top of my head: The early documentary emphasizing just how prosaic Royal Family life is; her stripping Princess Diana of her title (apparently, this was pushed by PC but, still, I believe HM has the ultimate say) -hard to fathom it, as PC, by all accounts, was unfaithful almost from the get-go; her appalling lack of simple respect for PD upon her death, at least until the Prime Minister moved her to show some; and her utter lack of perspective on her "favorite son". (I'm no Princess Diana fan, by the way, but those things were awful.)
I get the impression that she has always had a very firm idea on how she should behave, but no concept that most of those around her have absolutely no idea nor, apparently, do they care. She can be woefully out of touch with the motivations, weaknesses, ambitions, struggles, etc. of those around her. Princess Diana is one case. A very young woman, marrying into the RF but also an older man would be challenging enough. Then to have him running around with his ex and the Queen, essentially, with the attitude that she should just put up with it -no wonder there was no love lost between the two. With some empathy, advice, support from HM, that PD documentary could likely have been staved off.
Then, there's the DoS: Did anyone, ever, anywhere, think that an actress and celebrity would be a fit for royal life? An American at that, where the very idea of monarchy is practically anathema -certainly foreign. We fought a war over it, after all. Actresses and celebrities, far from "keeping a stiff upper lip" are known for attention-seeking, publicity seeking, camera-seeking behavior, and for wanting to give opinions on every subject they generally know nothing about, so as to appear like they "are" someone; rather than simply someone who "plays" other people. They constantly seek self-validation.
My bet, anyway, is that upon HM's retirement/abdication, the British Monarchy will be irrevocably changed. The few aspects of HM that kept the RF from mere celebrity status aren't much apparent in the next generation, with the exception, maybe, of PW and Kate.