I think there is always room for improvement, and I by no means believe that belts are a "dead" platform. I feel they carry many advantages, and can be and are just as competitive as shaft. I think that a drive train being belt or shaft doesn't determin whether the car is good or not, its how its executed, and how the other components are too.
I really do hope that Tamiya do bring out the TRF 415 as I am extremely fond of my trf414m wcr and would not like it to be the last in the series, I want to see the series win more!!!