Had good experience of BA Holidays over a hotel change, and even a courtesy call to check everything was OK once we were in. However they are a small team and are largely working from a booking screen / hotel database, so they may well not appreciate differences between hotels (size, location, whatever) that are important to any particular customer. Hence the importance of doing your own research before accepting any alternative.
Back to the OP, I would say that hotels that go out of business have a habit of popping back up with new owners, bailout, takeover by a chain or whatever. Of course that may be less likely for a while during the current downturn.