I've just been looking at my copy of Misner, Thorne & Wheeler. There is a spooky footnote in the introduction which must have been added late in the publication process, saying
As of April 1973, there are significant indications that Cygnus X-1 and other compact x-ray sources may be black holes.
When they wrote the book there were no known black holes, and I don't think everyone even thought they were physically plausible. I bought it in 1985, Hawking conceded his bet that Cygnus X-1 was not a black hole in 1990, and Thorne Weiss & Barish won the Nobel prize in 2017 for the direct detection of gravitational waves, from black hole / black hole mergers among other things.
We're living through a golden age for astronomy and astrophysics. All the theoretical physicists who mourn the lack of progress in fundamental physics are just not paying attention: something that some astronomer observes or has observed is going to be the key which leads to the next big revolution in fundamental physics. They've already observed things which mean that the form of the equations of GR is now different than the one in MTW (there's no index entry for 'cosmological constant' in that book that I can see).
Unfortunately this golden age will be one of the last gleamings of enlightenment as our civilisation hurls itself into a long darkness led by men1 with the minds and behaviour of infants. I hope that the discoveries we've made will not be lost in the long dark age, but it is almost certain they will be.