Mainly, Core needs to replace its PoW function, preferably to a function which make any effort to create ASIC for it economically nonviable.
Guy is pushing for a change of PoW algorithms to be essentially GPU-only (that dynamically change every ~12K blocks as well as a phase-in and phase-out from previous and next functions on each end) in case the hard-fork of Classic takes place. This would prevent any kind of ASIC development from taking place on Core chain, and act as a defense against 51% attacks from the Classic chain. The real solution is to simply not allow Classic to take place.
Nothing about PoS that I read in that post anyways.
Ask yourself this, why would Guy Corem be pushing for a defensive GPU-only PoW system that would essentially end the hardware development by his company, unless he truly believed it was necessary for Bitcoin's survival? I sincerely do not believe it to be out of spite.
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"In the event that the Classic activation threshold is not met, Core should remain with its current PoW algorithm. As the older members of our community may remember, when faced with Global Thermonuclear War, the only winning move is not to play; a GPU only PoW hard-fork is Bitcoins response to a politically driven consensus break, and should the hostile hard-fork not gain traction, we do not need the self-defensive one, either.