Looking at the die shot [1], they have plenty of space for cores and cache if they remove the GPU. Surely it's not that simple, but I believe they should be able scale to at least 8+4 cores without large interconnect changes, and at that point they are already knocking on the 5900X's door.

[1] - https://images.anandtech.com/doci/16226/M1.png

I would suspect by the time that product releases, AMD will be allowed some 5nm fab capacity for a future Zen product release.

We’ll find out this year.