The carry-free nature of residue number system (RNS) has introduced it as an efficient unconventional number system which has attracted lots of researchers for many decades. Distinct aspects of RNS systems such as its application, architectures and implementations were considered. Although, all these researches were done, still lots of leakages exist that need to be fully investigated. Furthermore, new technologies such as nanoelectronics cause extra challenges. In order to facilitate professors, students and all RNS researchers works, we are going to study these emerging challenges in this paper.