I've asked in heaps of stores here in France and everyone is really suprised when I ask them if it's stopped being made. They all say - well we still have heaps and we haven't heard anything about it stopping.
But mind you, I don't think they're really on the ball here. I went into one shop to see if they had any medium format film and the girl looked at me and said "they don't make that anymore" in a really matter of fact way, she was so sure! and I just said - "yes they do". She had to ring her boss to see if they make it. Crazy french shop assistants.
But i'll keep asking here - You never know I might supplier of Velvia 50 to the USA in a few months!