If you're using Lightroom, the more powerful graphics cards help, especially on 5K screens and the XDR. I would wait for the 5700x if you can; it should have similar performance at a lower price point, at least for Photoshop and Lightroom.
More graphics power is always good for Photoshop at least. My understanding is that AE doesn't benefit a lot. Depends on your budget, the Radeon Pro Vega II is a workhorse, and available, but more expensive.
I think the big thing that keeps me waiting is that the W5700X is likely going to be a lot cheaper than the Vega II. The big question mark really is what sort of premium does the MPX version carry over the W5700.
It really depends on how hard your process pushes the GPU. What I'd do is actually have Activity Monitor open and run a GPU history window while doing your workflows where you are looking get extra performance. If your GPU history is maxing out during those, you can probably get more performance from an upgrade. If it's not then you probably won't get a huge boost, and it's probably better to save your money.
I figure about $1.2K for the W5700X. About twice the cost of an RX5700XT + $3 to $400 for the added RAM. Seems Apple values the base 580X at $400, about twice the cost of a top end RX580. I get $400 by looking at the price of the Vega II at $2.4K. If we multiply $2.4 X 2 we get $4.8K. Two Vega IIs cost $5.2K. So the second Vega II costs $2.8K.