There is a massive difference between procedural enroute and busy radar - if you can't see that then get out and have a look around. That doesn't mean that a procedural enroute controller can't transition to a busy radar environment. A number of TOPS guys have done just that in recent years in international environments. It just takes a bit of work - but then again it takes a bit of work for anyone to retrain on new airspace.
I don't think the new guys will be at a disadvantage when it comes their turn to jump ship in 5 years.