Maybe we just have to accept what SUP surfing really is - bloody great fun, but not as good as short-board surfing at the elite level...
The WSL runs a great comp because there are zillions of people watching Kelly and Mick etc. do what they do so well (and even with that I think they almost went broke a couple of years ago). The guys you see surfing SUP are either essentially short-board surfing (but not as well as Kelly/Mick) with a paddle in their hands (e.g. in a barrel or on a BIG wave), or they occasionally do something with the paddle that enhances the ride - but something that is not appreciated by non-SUP riders.
It may sound cruel, but when I see the great (young) SUP riders in vids, I think they are only on the video because they are not good enough to be on the surfing world tour. They are 100X better than I am, and they inspire me, and I love watching, and it makes me want their board - but I am not the general viewing public. (But most of them are on tiny boards that you hardly recognize as a SUP.) And when 95% of proners don't like SUP riders (putting it politely), there goes a big chunk of the market (unless there is a chance of the competitors being taken by sharks

).
So it seems to me that unless the SUP makers bank-roll the event, they won't be viable at the international level. Or SUP riders need to find new things to do with the paddle that get the attention of the general viewing public.
To set the record straight I am a 53 year old SUP surfer who started SUPing because of a dodgy back, but who would never go back - SUP surfing is way more fun IMO.