If you're talking about the SCUMM engine, that narrows things down to a subset of LucasArts and Humongous Entertainment games. LucasArts because they designed the game engine, and Humongous Entertainment because they licensed and developed it further. I haven't heard of any other company licensing it.
But obviously, you're talking about games that ScummVM can or will run. The
Engines page lists some work-in-progress engines, or games that could eventually be supported by existing engines. The "Future Engines" section should probably be taken with a pinch of salt. For instance, I don't think there has been any real news about
Discworld for over a year.
Of course, there's always the possibility that someone will arrive out of the blue with a new engine and ask for it to be included into ScummVM. But there are so many interesting unsupported games out there, so even then it could just as well be for some completely unknown game as for any of the ones you mention. We don't get to pick and choose.