Let's hope Zen2's memory controller improves that.I thought it was more to do with it running at its advertised speed more than anything.
i.e. you might buy some 3200mhz micron/Hynix based memory, but you may only get it to run at 2933Mhz, but if you buy 3200Mhz Samsung b-die memory, you can basically guarantee it will run at that advertised 3200Mhz

3950 just seems like a moderate clock bump, not an extra 4 cores/8 threads. Unless they think/know they have the market sewn up and don't want to launch it until Zen 2+ in 2020.