Seen it happen with a private museum out on the east edge of Saskatchewan several years back. Some of the locals were quite upset that the family was not able to keep it going, as they had donated some of the displays that were sold off that day.
Most museums that accept donations now have a "no-commital" understanding in their acquisition policy.
For instance, the American Precision Museum has their version:
http://www.americanprecision.org/images/pdfs/2010_collections_management_policy.pdf
Materials are acquired for the collections with the understanding that they will be kept for the foreseeable
future. Nevertheless, the museum reserves the right to remove objects according to its policy. Except
under extraordinary circumstances, the Museum will not acquire material with restrictions or without also
receiving complete title.
Note here that complete title means they can do as they please. Scrap it, sell it for funding, donate it to another museum, or even a private collector more capable of preservation. The museum will do as it will. And now, given the world as it is and the vagaries of human interest, a previous promise to keep, preserve and protect is set aside.
And generally I support this thinking. NOTHING is forever - as much as we might wish it.
The good thing is generally once things make it to "museum land" - they are henceforth considered of value and will be treated as such going forward.
"See this Steam Engine" my Manchester, NH friend says to me very proud. "THIS we bought at auction at the Henry Ford Museum in 1983"
He was referring to an Atlas Steam Engine which the tag showed has having been bought by the Ford Museums in 1929 from a shop in Nashua, NH. My friend considered he was returning the engine to it's "rightful home" in Cow Hampshire.
But other than originally having been used in Cow Hampshire, the engine had little to keep it here - or bring it back.
It is, after all ONLY an atlas steam engine - which was an "ok" engine of it's era. There were better engines.
And this is the way of it. They are only "things." And someone, somewhere will alway appreciate them.
Just as Jay Leno's former Henry Ford Museum engine is now "Jay Leno's Engine"
Joe in NH