The Retro valve is quite honestly the savior of Mags held by current owners, bring their speed up to that of the RT which is quite sufficient to keep up with any marker, electro or otherwise. A lot of people will tell you that the RT is past its usefulness. NO! You can still be competitive with it, but it's just not an electro. It is consistent, functional, and fast--it's just not AS EASY to shoot as fast, and it isn't as light as some guns today. Like a Cocker, which no one disputes as being a competitive gun, it only chops when the shooter doesn't hand the trigger how it needs to be handled. That takes getting used to, and a lot of people aren't that patient, especially when they can get an Impulse or BM2K for less money that doesn't short stroke at all. So you had the choice between the two top non electros, and when stock Cockers started getting good, stock Mags started getting gone.
So are RT's and retroMags dead? No, but they're out of the limelight.