I have a friend who does only pantos and custom free motion on her longarm. I think all her business is local. Another friend has recently added a second machine with robotics because she had so much business (also local), including quilting that she donates to the guild. I have a longarm (no robotics) and do only free motion quilting for myself and occasionally for close friends. I've thought about doing it as a business, but decided I didn't want the hassle. If I were quilting as a business I would plan to add the robotics, since that's more profitable (and easier on the body) than just doing pantos and free motion.
I think there are people who are willing to pay for custom work if it's done very well. However I don't think that's the way to go in today's market, unless you can build a name for yourself as a custom quilter. Custom work is time consuming, and most customers don't want to pay a decent hourly wage for it.
I think there are people willing to pay for pantos without robotics, but they expect to pay no more than they would for the panto done with robotics. And the pantos with robotics have an edge in that they can be scaled up or down to change the density. Most computerized systems come with more designs than a quilter without computerization is likely to own in paper form. I realize that adding robotics is costly, but I think it would add to your bottom line in the long run.