Foveated rendering for virtual flatscreen

One thing I've rarely seen discussed, is the possibility of one day eye tracked headsets / screen glasses being common enough, that we even start getting foveated rendering support on flatscreen games. (Or some kind of universal solution being invented, like what Valve is rumoured to be working on.)

Could it give enough of a performance boost to help underpowered hardware like Steam Machine or Steam Frame standalone run some higher end PC flatscreen games? Every little bit helps, maybe?