And what happens on Zen6 if more than 12C will be needed.
That question amounts to "what happens in 5-8 years".
Right now, the 9800X3D still demolishes the 8+16 285K in gaming, and a 50% core upgrade for Zen6X3D will push back the "not enough cores" point by a bunch more years, so whatever.
Games are developed with the lowest common denominator in mind, that's currently 6C+SMT on AMD's side and 2P+8E/4P+4E on Intel's side.
On consoles it's currently 8 Zen2 cores, and will be 10-11 Zen6(c) cores with next gen consoles.
So yeah, 12C+SMT will be a non-issue.
Look at E cores track record they are unlike P cores they did 2 30% IPC Improvements in a row i don't have any doubt they would do 20% IPC Improvement this time on top of introducing APX/AVX 10.2
The last one was a jump from Intel 7 to N3B, and accomplished by >=60% more area, normalized to the same process.
Skymont is a massive upgrade, no doubt, but it was far from free, and node bumps are getting smaller from here on out.