I've been a Pronto user for less than two years, with a RU950 (TSU3000) and more recently a TSU9400. I do feel sorry for those working at Philips and dealers/integrators that were working alot with Prontos. I don't feel too scared about the future though.
As I said, I got a RU950 after it had been discontinued for some time. I could still use it with available software and didn't really require updates. I guess the same thing will happen with the TSU9400 now, although I was planning on learning ProntoScript and program my own 2-way module for my future Onkyo TX-NR808 receiver.
Some others already said it wasn't the end of the remotes that we own, as long as they work, and I agree. The annoyance is that we won't be able to use the modules and configurations we'll have made on other newer remotes. For now anyways, as we still don't know if the Prontos will be re-branded or if someday we'll find out how to decode and use xcf files.
I'll just keep playing around with my TSU9400 and wait for proper solutions to replace it with : A tablet about as big as a TSU9600/9800 with the usual hard buttons and an opensource OS (not an Apple-based product).
Or maybe the Pronto division will be bought off by another company. Who knows, I'll wait and see, while my remote still controls my current and future equipment.