Only a very small number of games are cpu bound and in most cases the ones that use a lot of cpu care more about the clock speed of a couple of cores rather than the total number of cores.
So far I have not seen much in rumors of if the 9950x3d is going to have the same issue as previous amd cpu that only have the cache on 1/2 the cores. This is very messy to get to work correctly since some application can use the 3d cache and other care more about the clock speed. Maybe they will sell a unit with cache on all the cores.
I am going to bet any raw performance gain will make very little difference in most games and I suspect even after the scalpers go away the premimum you pay for a 9950x3d over other x3d cpu will not be worth it.
Now if you do a lot of non gaming production type work the value of cpu with more cores might be worth it.
I suspect though you will wait at least 3 if not 6 months out before you can get cpu for list price. Microcenter would be your best option to try to get one for list price on day 1 but you will have to stand in line at store open to get one.