I believe that Intel would agree with you. And you may be right about foundries as well, except for one fact. Namely, that if foundry customers say they want to use SOI wafers, then foundries will let them. Period.
Solitec is not the only supplier of SOI wafers. In fact, nearly any wafer maker can be pursuaded to create functionalized wafes for special purposes--especially at the 400 percent premium they can charge!
IBM continues to make impacts on technological progress(es) and what they are doing has R&D value and it contributes to the evolution of foundry process(es). But at the end, Foundries may not use these processes as a baseline processes for their customers. Simply it may not be THE process(es) foundries can use for baseline process economically.