To be honest I don’t see us getting extended functionality out of Sorcerer thralls. We might get something where we expend them as pawns. But they will never be some sort of helper or partner. Sorcerers in the Hyborean Age are extremely jealous of one another and groups of them while powerful, are quite rare. And even when they do work together there is intrigue, plotting, conspiracy, and violence amongst them on each other.
If we had a sorcerer thrall doing spells for defense. They would have a decent chance of turning on their master should they ever show a moment of weakness. They would be less reliable than demons.