Well how are you making them, how many are you making and how much do alternatives cost?
Economics vary wildly over time pending circumstances, but are irrelevant to the question of whether something is a technological dead end. To be a technological dead end there must be an alternative technology that accomplishes the same feat in a fundamentally superior way, such that regardless of the economic situation or future development it always makes sense to go with that alternative outside of niche applications.
No, the problem here is there are only a few trains in the world that need this technology. Thus there are very few to amortize the costs of more R&D over. Tilting as a whole is a dead end: passengers get sick where it is used. The replacement is don't tilt your trains on corners at all - thought there are other technologies that are already more reliable as well if you must.
