AMD paid a fair bit of money to get the WSA with GF amended, which they wouldn't have done just for fun, and part of the agreement is that they pay on a per wafer basis for anything produced elsewhere - with the current terms it isn't commercially viable on products that aren't big ticket/high margin.
From the looks of things to produce 16C dies usable in such a configuration wouldn't really be possible without EUV on GF 7nm while TSMC has a bit better DUV lithography allowing for smaller minimum gate pitch, etc. on their first 7nm process which might just about make it possible. (People can BS about GF - but 16nm shows just how big a margin there in in reality between TSMC and GF's lithography and maturity and the first round of 7nm without EUV will rely on that).
To quote someone else heh:
"GloFo has managed to get AMD to pay for GloFo's own incompetence -- and do so twice!"