Not well. And don't forget PCIe 4.0.
What Apple did was to go with Intel's server socket (LGA 3647), which Intel is now pushing for workstations, instead of the LGA 2066 on which they introduced the Skylake X-series and Xeon W.
The new Mac Pro's baseline CPU is certainly not 28-cores, though. I think they have 4 different CPU options, and going with the top-end 28-core model will probably add more to the workstation's price than the cost of a decent, small car.
One way I think Intel enticed Apple is by unlocking an extra 16 PCIe lanes, so they at least can match ThreadRipper's 64 lanes. Also, LGA 3647 has 6 memory channels, beating ThreadRipper's 4-channel support. Of course, Apple probably could've sweet-talked AMD into issuing a special, high-clocking, 32-core+ Epyc model, with all 8 memory channels enabled.