In reply to P.Nadatajan.

For the user devices the dependency will be support of the new radio interfaces, initially grouped as <6GHz and >20GHz (termed mm Wave) frequency bands. New chips and hence devices will be required to leverage these, in conjunction with current 3G and 4G bands. Other 5G aspects in the network; like adoption of NFV/SDN for a distributed cloud architecture, won't have device dependency, and even current 3G and 4G users will benefit.