Essentially a merge of several disciplines that gets lumped together under the IoT umbrella (or Internet of <foo>) umbrella. The term convergence applies IMO because no matter your background chances are good you find at least 1 foothold in a specific area:
* Web technologies (REST, Node, ...) a lot over UDP (e.g. CoAP)
* Embedded Engineering (RF, SoC, HW, etc)
* IPv6, Low power radio networks and WSN's
* Security & Privacy (biggest issue
Internet of Things Protocols & Standards: http://postscapes.com/internet-of-things-protocols
My background for example is backend web technologies & infosec hence in my case the perfect starting point was the Web of Things (WoT) though somebody closer to the metal would maybe choose to enter the industry via another domain (consumer electronics, automotive, ICS/Industrial Automation, ...). I discuss general IoT topics through the angle of InfoSec on my blog for example but I know little about RF engineering or low level chip design.
"You can't know it all" is even more true in IoT IMO, ...
I would add "Edge Device Applications" as a new entrant to the IoT software marketplace as well. Platforms like PTC ThingWorx, GE Predix, MS Azure are essentially becoming app stores for edge industrial devices where developers can create applications for IoT nodes/gateways.
Also ML/analytics are starting to enter the equation as companies try to figure out how to optimize the tons of data that is being pushed through IoT networks, and feed it back down to improve processes.
"You can't know it all" is even more true in IoT IMO, ...