My bad, then. I was under the impression that they had equipped the ones on the 7 to run with CBTC.
Still, I assume if, come 40-50 years from now, the whole system is CBTC, they might possibly be able to equip the museum fleet to be CBTC-compatible. If not, assuming we still have wayside backups, I figure they could just run those trains during periods of low usage to minimize service disruption.