One possible way we might have more graceful fallback now is to have some <noscript> content.
It's a deal. If there was a "For the latest announcements, see ......" or "Site announcements" (hyperlink), or just "Announcements" (hyperlink) still visible for us text browser users, I would let you off the legal hook of cheating users with disabilities. But it would have to be at the same spot in the page where you show other users the message, not just in the sidebar or something.
That way the caches would not be disturbed all year, and you could show one thing to Google, and something else to most users, if you insist.
I could then put that hyperlink on my WWWOFFLE list of pages to monitor... indeed maybe users could put it on their watchlists, if it is a regular page.
I don't know about the frames stuff, but it doesn't sound like it would work on the large range of devices, which is actually what I'm concerned about, and not users with disabilities, who in fact I've hardly ever met, (except me: Limited Edition brain :-))