Hmm...
I have now seen 3 different 1971 release prints, all have Buck Rogers, I'm getting pretty sure that the "Things to come" is incorrect.
Also, Lucas messed with the audio on the Buck Rogers intro in 1971, (five points to the first person that notices the replaced line) replacing some of it with new audio to 'make a statement' about THX, that would also seem to indicate it was his choice to have it there.