That would have been interesting. I've been rewatching a lot of Man From U.N.C.L.E. episodes lately (I'm recording a 2am broadcast on ME-TV as I type this), and there are some significant differences between the TV and theatrical versions of some stories. Heck, they even built a few new episodes out of the extra scenes they shot for cinemas! Can you imagine all the canon wars we'd have if TOS had done that?I wish TOS had gotten the "Man From U.N.C.L.E." treatment, with certain episodes expanded with new footage and subplots for theatrical release.
The pilot episode of the 1980s Buck Rogers in the 25th Century TV series was shown in theaters as well.