I remember, about 5 years or more ago, a Fuji lab engineer telling me that R&D had stopped in RA4. How true this was I don't know.
I do know that a lot of the small minilabs switched to dry lab (inkjet) partly being pushed by the local Fuji rep and being told of huge savings in electricity charges. For example a (wet lab) Frontier 350 laser print-processor unit can consume 4 kilowatts (approx) of electricity when running.
What they weren't told was that the cost of ink was high, so that the unit cost per print of a dry lab was between 2-3 times more expensive than a wet lab.
So for the small volume lab, the dry lab looked good, but once you had any sort of decent volume the wet lab won on print unit price and speed.
Big online print labs, for example, Photo Box (Ire, Uk & EU) use RA4 prints. AFAIK, Snapfish uses inkjet but they are owned by Hewley-Packard.
I think the Fuji Instax has reignited a desire to have prints made for digital files. But this time around the customer is only printing the ones they want and they want different formats ( imitation polaroid prints were a craze a few years ago). I don't think we need to worry about RA4 disappearing just yet but maybe Henning Serger could give a more accurate picture of it.