It would be fantastic if they manufactured new Transtalks. Many of my clients opt for the Panasonic systems because the 3910's are hideous and feature-defficient. I actually installed a Partner in a residence once, the two 3910s performed so poorly, I took the entire Partner out and replaced it with a Panasonic. The downside of the Panasonic cordless units are they can be somewhat overwhelming. The Engenius sets perform well, but a fair amount of my clients also stress aesthetics.
I'm definitely with Dex, if a viable Transtalk telephone was introduced, it would be a great thing.