In my opinion, PowerBuilder is the modern-day COBOL or RPG. For business functions, it's just too easy. The DataWindow has been a great asset to the PB community, and now the DataWindow.net is expanding that into the rest of the .NET world. For in-house developments, PB is far easier and cheaper, and from what I've seen is still the more logical choice for small to medium corporations.
Those are just some of my feelings on the topic, but as far as the outlook on the lifespan... I'm at a loss.