Welcome, John, and why not join us (for free) and continue interesting discussions?
I certainly have seen 'non-folkie' pub audiences sit up and take notice to traditional music and often it is related to a rather contemporary arrangement and sound, not so much the actual song itself. This is of course a matter of taste, but a number of individuals and groups have made excellent livings from 'folk' treated in a contemporary fashion. Some past ones might include Peter, Paul & Mary and Simon & Garfunkel. Some newer folks doing similar work include The Mammals.
I wonder if finding some relatively obscure material and giving it a new setting would help keep interest up in some of the settings you describe? The songs that have survived for many decades, or centuries, have to have something powerful going for them and your audiences may be quite ripe for them, even if they never consider themselves 'folkies.'