Look in future developments and state of the art of Fractional Order Modeling and CONtrol at the following site: http://fomcon.net/. All the answers are at your disposal. Good luck!
The answer to this question can change on a weekly basis due to the number of researchers dealing with FOC. The best way is to look into the journals and texts.
Anyway, I see development on the following based on my observations:
1. Tuning methods for FOPD, FOPI, and FOPID controllers
2. Electronic realization of fractional-order controllers
3. System identification of systems using FO models