Best case for her is an unremarkable middle-ranking Party member who muddles along playing the system to her benefit as well as she can. Worst case... well, she was already purged once, it wouldn't take much at all for her to be purged again. Especially as an intellectual from bourgeois parents with counterrevolutionary beliefs.
Either way, nobody's heard of her.
I agree. I think Ayn Rand becoming the woman she became was very much connected to her status as an emigre in hypercapitalist USA. If she stays in the USSR, her political activism is probably confined to mouthing-off Bolshevik authority figures, an activity she would likely curtail if threatened with the barrel of a gun. And if not, she's eventually shot and buried in an anonymous grave somewhere.