Peter,
If you can find the time to login to SAP's abominable nosupport site 10 times, you'll find that support for 12.1 ends in Nov. 2014, 12.5 is end of life in August 2015 and 12.6 is end of life in July 2017. This will be the first time I can recall when there will be only one version of PB in support and says quite clearly that there are no plans in SAP for PowerBulider beyond 12.6.
It's all very well for Dirk Boessman to prance up and down a stage and spout on what he's *thinking* about. (I should put a picture of Nero and Rome burning here). I'm afraid I live in the real world and am not prepared to bet my future or that of my business on the alleged musings of a some unknown in a company that blatantly has no interest in their customers beyond screwing money out of them.
I would suggest you do what my team is doing and look at alternatives to PowerBuilder. Sad though it is, I'm afraid SAP really have killed it, they just won't say so. We're not even thinking about a move to 12.6 - the trial migration I did on a target with four objects simply lost scripts, and reading comments in here it's bug ridden anyway. Given how little there actually was in it, why would you bother?
As for Appeon, everything you need to know is found in another thread on this group.... "appeon_workarounds.pbl" 
Paul
See how long before the mods clobber this one 