So. First off, a big thanks to everyone who weighed in with their opinions in the previous post.
The results are as follows:
Fifteen people are okay with there being no volume 3.
Eleven people would be unhappy with me skipping to the omnibus, and might not buy it, and might wait for the omnibus of future projects.
If I filter out the people who are fellow cartoonists with their own piles of books to find space for and hassle with maintaining the stock on, it shifts to ten okay, eleven not okay. That’s pretty much an even split.
Even if I don’t filter out the people who know the special joys of self-publishing, 1/3 of this sample of my current core audience saying they probably wouldn’t buy an omnibus is definitely something to worry about. So I guess I will be sucking it up and building my Kickstarter campaign around reprinting book 2 along with book 3 in sufficient quantities to hopefully run out of stock of all three of them around the same time, and wait for a year or two before I can publish the omnibus.