ITER is also supposed to be the final step before a commercial reactor. If SPARC works well and they can keep the pace they're at to make ARC, then ITER might be a dead-end in that regard, no?
Iter's is supposed to have a successor, DEMO, which would be the final step before a commercial reactor. It is doubtful whether DEMO will ever be built.
We already have enough experience that makes ITER obsolete.
Newer designs will have a much thinner central column and stronger magnets, resulting in much better confinement. And high-temperature superconductors will an order of magnitude cheaper.
Right now, ITER is still needed to get information on plasma properties at the temperatures required for fusion.
