I keep on hearing that TR3 will eventually come to market, including a 32c with 'monolithic' RAM. AMD however may want to see what the new Intel HEDT line will bring to the table, and probably move TR3 upmarket a bit more... and the 3900X and 3950X are opening important segments and price points already, anyhow.
There's also the fact that between 8c and 16c Ryzen 3k and the lucrative $erver-chip market (7nm Epyc, facing increasing demand), a lot of binned 8c chiplets will already be spoken for. Still, like other posts above, I prefer / need at least quad channel RAM and more PCIe lanes than 3950X offers (ie. partial productivity work w/ extra raid cards, Intel network server cards etc)