At my present carrier, the 80 knot call is normally acknowledged by the Captain, but if it is not, we have a second call at 100 knots (mainly to varify/compare indicated airspeeds) to which the Captain would normally reply (check)...if no reply received, F/O presumes incapacitation, and either continues (preferred, except if rather light), or stops.
Works well, and eliminates much drama.
Keep it simple, for best results.