Just saw the Hawaii news hare on Maui and they always and with some viewr pics from around the islands. Today two of the pics ware SUP surfers ripping up Pipeline/backdoor, catching tubes going high speed etc. Every (relatively windless) day on Maui you see both beginner surfers and veterans SUP and you also see a few "progressive" SUPers on shortboard SUPs basically doing shortboard style turns.
So, maybe the popularity will eventually wear off a bit, but I think "the tool" is here to stay. It just opens so many doors. But I agree it does not have so much to do with windsurfers other than being a natural extension of the time on water (both in the surfing direction and in the paddling direction).
I also think that for wave sailors, SUP surfing will come very natural. You have the same overview like when you're sailing, you're catching waves in a similar manner as when light wind surf sailing, you even set up a bottom turn in a similar way ( the paddle steering motion being rather similar to what you do when you move your back hand on the boom to power through a bottom turn).
For me, being a fairly competent wave sailor but a lousy surfer, SUP have really been a revolution. Not only have it offered good surfing fun on light wind days, I've also caught waves with my son riding with me, my wife have caught her first waves and the SUP have made me learn more things which will help my regular surfing then I have learned for a long time. I've even learned stuff that helps my sailing.
I could probably have had fun also without the SUP, but for me I can't really see you guys can see a new toy (or tool) for on water fun as something negative. If you're not attracted by it, just don't try on (or buy one).
And by the way, I haven't even got the chance to use a Starboard SUP yet so I'm not being "bought" into this.