Having worked in music retail until 2010, i know there is a market for oldies/old-school music. The problem seems to be too many compliations with the same tracks. By now, most people have the hits. They are looking for rarer songs and the licencing is probably cost prohibative or in dispute.
Even Butterball stopped releasing compliations, and those sold better than some recent titles.
If someone had the money to get better tracks, and priced the CDs competitavely, they could still sell.