vast majority of chips are still at nodes above 28, and new chips for IoT will be lower volumes than the highest volume, high-perf chips people love to cite -- so plenty of volume is up for grabs.
got a smartphone? Then you've got an RFSOI chip in it. Wafer technology from Soitec, >20 billion chips shipped, 100% market penetration. Got a car? SOI-based smart/power chips are used by virtually every carmaker on the planet. So yes, they know how to do volume.
SOI wafers also made (using Soitec mfg tech) by SEH (the world's largest wafer producer) and Simgui (China)
SOI wafer cost is amortized, because the fab needs fewer processing steps
FDSOI is hands down winner when you really care about power & leakage (like NXP's new i.MX 7ULP - and that's at 28) and bursts of very high-performance just when & where you need it. Or automotive, where SOI is up to 100x better than bulk in terms of SER.
Samsung's 28FDS is shipping in high volume now - they were ready when NXP needed them. GF's ramping this year with 22FDX - and they are already increasing capacity in Dresden by 40% and building a fab for FDSOI in China. But when you're talking about these sorts of chips, many with mid-range volumes, the math is different, so you gotta look at it on a case-by-case basis. Which is right for your IoT chip? 22 or 28? You gotta do the math -- there's no blanket "oh this is faster so it's better" thing going on any more. And if you're going to be integrating RF & analog, FDSOI is way more attractive. Ditto if you're headed for 5G.
back-biasing -- it's an old trick you just cannot do in leading-edge bulk - be it FinFET or planar- but you can do with amazing results in FDSOI
Hey, you know, there's an FDSOI tutorial day in April in Silicon Valley -- maybe you should check it out?
Over at SemiWiki this guy has this 22 ULP announcements as his number one highlight from the TSMC Symposium. Also, he said that TSMC inserted a comparison slide to 22 FD-SOI. He said the Ion and Ioff currents are right on top of each other.
If the new TSMC 22 ULP is close to 22 FD-SOI in power it will win. SOI wafers are more expensive than normal wafers. They require a bunch of extra processing steps to make them.