It's very strange that she would be fine on Monday (at least enough to stand and take pictures), and then suddenly not fine on Thursday without some kind of major medical event that would require hospitalization. Unless something sudden happened today, she's already gone, and they're just waiting for the family to arrive. Or maybe, as some have speculated, she had an undisclosed illness that the family has known about for awhile.
I'm a bit

at the people who have gathered at Balmoral. FFS, give the family some privacy.
When I moved to the UK, I always hoped she'd live long enough to be the monarch when I became a citizen. At least I got to stand next to her picture, swear my oath to her, and have a passport in her name.