You're right that the Milky Way is not the sort of monster I was speaking of. Many large clusters of galaxies have a giant elliptical in the centers. These monsters have central black holes around a thousand times as massive as the one in our center. There was a story a month or so ago about a galaxy falling in toward the center of one of these clusters and getting the gas and dust blown out of it.

These clusters have relatively dense very hot plasma blowing out of them. What is left after a smaller galaxy gets blown out is a collection of stars and dark matter, and no new stars are formed in that galaxy after that. Such a galaxy will fairly rapidly become an elliptical.

I believe that it is very unlikely that any of the stars of an elliptical will suddenly lose their orbital momentum and fall in to a central black hole. The outer stars will get tidally ripped away from the smaller galaxy by a bigger one, but the inner stars will remain nearly undisturbed.

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Forming opinions as we speak