I think that we're likely to see older tech on SS bikes, for several reasons. First, SS is just a good use for old parts. The parts that deteriorate and are hard to mix and match, are the derailleurs and shifters. SS is what's left.

Second, older frames are more likely to have horizontal dropouts. Third, there was a time period of maybe a few decades when there was very good interchangeability of parts such as BB's, so you're more likely to find the parts for a SS build in your bins if you start with a frame from that era.