^^
Yes, I think companies that typically cater to DIY and people on a budget, like Sans Digital and Rosewill, just can't make the numbers work to develop Thunderbolt products under license to a smaller group of buyers and a very slim profit margin at their price level. But companies like Promise, Sonnet, and LaCie are probably finding a good deal of customers capable of spending at their level.
I think Thunderbolt is doing well at the moment. More devices are still coming out, lots of devices got updated for Thunderbolt 2, Apple is leaning hard into Thunderbolt (look at a Mac Pro ffs) at the Pro and Consumer level. The only competition is USB 3.0, which was an inevitable upgrade to the hugely successful protocol. Without Thunderbolt, everything would have to run off of USB or HDMI.
For Thunderbolt to go away Apple would also abandon MDP, which is unlikely due to all the displays out there relying on it.
I think Thunderbolt is guaranteed to be on every Apple computer for the next few years. It definitely needs to make some gains and find more adopters though. I think Apple and Intel are going to try to make it happen. Where they will have to fight is to make it relevant to the average consumer. It's the best professional option, but has little consumer necessity. If the Thunderbolt Display were more popular or affordable, people would love being able to use one cable to dock their laptop. It's an extremely strong feature on an often overlooked dock.
Fishrrman should just get a USB 3 enclosure.