According to Gallup, an increasing number of Americans describe themselves as "conservative", terrestrial talk radio's bread-and-butter political ideology:
However, a decreasing number of conservatives identify with "traditional values":
On the other hand, also according to Gallup, an increasing number of Americans consider themselves "libertarian":
And, today, nearly 60% of Americans share some libertarian views:
However, there are only a handful of libertarian hosts in terrestrial talk radio. This suggests there's a growing under-served demand.