Recommend read: http://www.nickhunn.com/lora-vs-lte-m-vs-sigfox/
I totally agree that we will see several competing protocols in the next 5-10 years.
Large network operators will focus on "NB-IoT" (correct new name: LTE Cat NB1), it doesn't make sense for them to push their competition (=LoRa, SigFox,...). Although LTE Cat NB1 may develop a significant market share, there is still room for competition in the even-lower-power/even-lower-price segment. And maybe most important: There is a demand for a technology that allows you to build your own infrastructure (like LoRa does).
So in the long run I expect at least one successful IoT protocol pushed by 3GPP, probably rather multiple protocols targeting different bandwidth needs. Those efforts will probably eliminate the "network operator start-ups" like SigFox we see today (that only exist because 3GPP doesn't deliver yet). Besides the big 3GPP players I expect several competitors who offer companies with a large or distributed campus (e.g., universities, hospitals, chemical plants,...) means to build their own LPWAN infrastructure.