Airbus sidesticks could be enhanced with a stick shaker, I suppose, but nothing more. Stick force must be totally independent of speed.
However I think that a loud "STALL STALL STALL…" aural warning is enough, at least for me.
In the case of the AF I don't think that a Boeing style fbw would have made any difference. They would have just done the same, pull the yoke till death. The airplane was airworthy, although somewhat challenging to fly.
It is human factors that have to be addressed. They were taken by surprise and they never recovered for it. They were so "in the red" and the tunnel vision so so narrow that they became effectively incapacitaded. Both of them. I wonder what rol had fatigue, complacency, health, etc in that incapacitation.