I believe that ST-Erikson are willing to pay extra for their wafers in order to reap the 40 percent savings in battery power, which mitigates the risk. The other guys are just validating that they can get the higher performance, and by the time they get to volume production, the price may have gone down due to high demand. Of course, bulk silicon will always be cheaper for the raw wafers.
As I wrote in May, ST-E reckons that w/FD-SOI's power savings, they can add a full extra day for smartphone users (see http://www.advancedsubstratenews.com/2012/05/novathor-smartphone-chip-on-28nm-fd-soi-st-ericsson-blogger-tells-all-pc-mag-sees-light/), which is huge.
And IBS says that even counting the cost of the wafer, per-die FD-SOI comes in at about *half* the cost of bulk (planar and/or FinFET) at 20nm (which ST has in very-fast-follow), because it saves process steps -- see http://www.advancedsubstratenews.com/2012/11/ibs-study-concludes-fd-soi-most-cost-effective-technology-choice-at-28nm-and-20nm/
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.