If you're shopping for a MacBook Pro or MacBook Air
The 13-inch Air and 13-inch Pro have both been very recently updated. The performance in these systems is considered excellent, especially now that you can get quad-core CPUs in the MacBook Air. If it's a near-term need, I would feel comfortable buying a MacBook right now. I'd bet the new platform isn't coming to those systems until 2021 at the earliest.
If you're especially focused on Photoshop or Final Cut
Consider waiting. The only real, solid details Apple offered on the new Arm-based platform was that Adobe had early access and already had Photoshop working smoothly on it, and that Final Cut was similarly up and running in native form. That means that future development of those apps may tilt strongly towards Apple silicon from now on.
See the full story here: https://www.cnet.com/news/apples-back-to-school-deal-get-159-towards-airpods-when-you-buy-a-mac-or-an-ipad/