Well with 502 and 511 upgrade kits it seems Tamiya TRF aren't killing either off just yet. A foot in both camps!
The new numbers:
501X then 511X thus as the middle number is increasing: the belt drive successor could be 521X
Thus for 502X: Successor 512X.
Upgraded 201X: 211X
if that were the case: 521X and 512X now thats confusing!
