Well, given this nothing is impossible: https://videocardz.com/newz/amd-reportedly-resumes-production-of-ryzen-3000g-seriesIt would be awesome but has anyone done this before or is it just a pipe dream? Off the top of head I don't remember anyone bringing in a new range once a platform has been superceded, they'd worry about cannibalising sales on the new platform.
5700X is a really nice CPU upgrade from a 1700X.
It wouldn't be much different than when they released the RX 590, which was released after Vega and was a straight die shrink of the RX 580.
Would there be a market for a Zen 3 with +5-10% clock speed?