radiation poses problems, but it has been since found that the radiation hardening measures taken on past IBM chips have been largely overkill for the application.
one can get near the same performance for much cheaper by using consumer electronics with redundant systems and a voting mechanism between systems.
Doubful, since they are not radiation hardened.
I could rather see a market for smaller size SSDs which contain lots and lots of chips and thereby have their own RAID subsystems.