YES! They can do a transfer of coverage and stay on the grandfathered plan or they qualify for an SEP if they’d prefer to go onto an ACA plan.
This is true of BCBSTX. And they’re the only ones that really matter since the others still offering individual health plans weren’t around at that time.
For Cigna, Aetna, UHC, and Humana, people who had plans prior to them discontinuing the product can stay on their plans, but not sure what happens in the above situation.