I have no idea, other than music historians. The WW1 generation is gone now. I know my folks and their contemporaries, who were of the WW2/Korean War era, couldn't stand Welk when he was on ABC. That was their parents' (my grandparents') music.
Surprisingly, there is some lingering interest in this kind of music, albeit small. Dick Sinclair's Polka Party still airs through the Cable Radio Network, and can also be found on YouTube and other online venues. Mr. Sinclair is still with us - age 96.