I'm also interested in the migration costs. Perhaps there will be a market for a migration service... though the TAM on that is probably small enough that it can't support a product-first approach.
Migration services exist today. Almost any of the ASIC backend service companies would take a contract to do a fab port. (Won't be cheap, though)
But these are services, not products. There's no one-size-fits-all way to move design Z from process X to process Y, for arbitrary values of X, Y and Z, nor is there ever likely to be.
And even once it's done, there are still costs to verify and test the results, which isn't cheap either.
Yes it certainly does seem like an opertunity for a specialist company to offer a full service, but aspects like that would usualy be handled for node shrink in colaboration with the node provider. But one aspect will be say for example a microicontoller used for sensitive equipment, the level of certification and validation from goverment/mil certification down to Insurance certification (Lloyds of London have a lot of standard in many feilds that have to be ticked from my experience in the Oil industry alone) that can bury many a product. Heck even your CE/FTC certification is not cheap so any changes,such as node size will see that whole process repeated - hence not all chip makers rush for the latest and greatest node as existing work and proven. Equally some equipment may well see issues upon smaller nodes due to the enviromental factors and smaller nodes more susptable to thinks like radiation in which some exotic space particle would be smaller than the node at larger size but smaller may well start to become an issue. Hence many reasons for legacy nodes still in play and utilised.
May well end up in a decade or two in which suppliers end up having to use China or Russia for production as the only way to get access to the nodes they need, and not like things like that not happened before thinking of how NASA for a while was dependant upon old tried and tested Russian rockets for space launches. Just hope this is not a future problem that is allowed to creep up and hit us all.
But these are services, not products. There's no one-size-fits-all way to move design Z from process X to process Y, for arbitrary values of X, Y and Z, nor is there ever likely to be.
And even once it's done, there are still costs to verify and test the results, which isn't cheap either.