Except there are two things wrong with that theory:
1) "IoT" is mainly a new name for something that has already existed - a market that has already been dominated by ARM: the embedded/microcontroller market. ARM has much better expertise in this market, better relationships, and better ecosystem, as well as a full range of products.
2) If Intel's chips weren't competitive in the mobile market (especially when you compare all three metrics of performance, power, and price), then why would they be in the embedded IoT market, which plays even more to ARM's strengths?