I woudn't. I'd wait. Or, if you can't wait, then I'd just go with something like the 3900x for now, that has the same cores as that 3950x, but has fewer of them. The 12 cores and 24 threads that the 3900x has are NEVER going to be fully utilized by any game, or even for any heavy multitasking process like recording, streaming, encoding AND gaming, that will see any significant benefit from having another four cores and eight hyperthreads unless you are simultaneously planning to do some REALLY serious multitasking by running a bunch of VMs at the same time. Then, and only then, do I see anything beyond a 12 core with hyperthreading CPU offering any real world benefit for a gamer or media and video application user.
Especially not if you DO want to upgrade when the new Ryzen CPUs are released. In that case, I probably wouldn't go with anything more than the 3700x for now, which itself is still a very capable CPU for practically any type of gaming, productivity or media system. Then, you can either keep the 3700x as a backup in the event anything happens with your newer Ryzen CPU, so that you are not out of luck and also have something to use for troubleshooting if you ever need to, or sell it, and recoup some of the investment to put back in your wallet after buying the Zen 3 upgrade when it becomes available.
As for the case, go for it if that's what you REALLY want, but if we're being honest, while it has ok reviews there is nothing about that case that really stands out when it comes to features or performance that would make me even think about saying "Well, maybe it's worth the four bills".