replaceState still works for changing the hash-code without updating the history list, so you can stay on the same 'page'. You can then read the hash-code using browsers like IE, just not create new ones. I used this as a quick hack to get permalinks on http://ares.aylett.co.uk/xkcd/ -- when you move (on at least FF and Chrome, but not IE), the hash-code updates, and at least FF, Chrome and IE can decode the hash-code on page load.

Not to say that I don't agree with your conclusions about infinite scroll -- I'd much prefer sensible pagination.