The only issue is profit margins. A Ryzen 1/2 chip(let) costs around $30, with the full TR/EPYC going around $140 total BOM.
TSMC 7nm costs more than double that ($70-80) so full TR/EPYC cost would go north of $300 in BOM.
And while due to different power spec, and leakage, more likely going to see 5Ghz+ Ryzen CPUs, on the other hand with a 16 core chiplet (used on 64 core EPYC) going to be tough to achieve, even if there is a cut down chiplet on the mainstream market and we don't see 16 core CPU on AM4.
Only if AMD moves the current Ryzen 2 (8 core) chiplet straight to 7nm we might say with certainty that is going to "drain the lakes"
Yet who knows.
And lets not forget, that we might see an 8 core APU...... that going to be truly EPYC