Yes, you will be able to buy the parts to convert it. Here is are the part numbers, not all of these parts are available yet, but will be very soon (June)

TT-02 to type-S conversion parts

Tamiya 54634 - Suspension metal parts set
Tamiya 54632 Front carbon Type S shock tower
Tamiya 54633 Rear Carbon Type S shock tower

and also to get droop settings sorted you can get

Tamiya 54638 - Steel rebound stopper (You will need two of these as they only come as a pair). You can only fit the rebound stopper on this steel suspension set, not on the kit set (I have been told, but cannot confirm). so if you have the S you can buy the seperate parts 54636, and 54637 which replace the kit part and are cheaper than buying the full set.