There is a lot of chatter in the Channel about Transactional agents being replaced by VAR's and Consultative Agents. I see Master Agents having to do a similar dance real soon.
Tech Data is one of the largest VAD (value added distributors) in the world. Most VAR's have an account with TD to buy hardware. The TDmobility division is a master agent for cellco services. Moreso than any master agency I know of.
Now Ingram, the other large VAD, just bought BrightPoint for $650M. 'BrightPoint distributes mobile phones and other wireless devices sold by companies such as Apple Inc, LG Electronics Inc and Nokia Oyj to customers, which include Sprint Nextel Corp, Vodafone Group Plc and RadioShack Corp." basically, BrightPoint is fulfillment - one of the big hurdles in the MVNO world.
Ingram is becoming a Cloud Aggregator and a Mobile Aggregator. Tech Data is a Master Agent for mobile, XO, some cloud and MDM. This might be where the transactional agents end up: as customers (or partners) of a VAD.