I have the impression with the release of 7.13beta and the wave2 ac-drivers, MT shot a bit in their own foot.
On one side it will make sure current owners of wap AC have no real incentive anymore to move towards AX. Potential missed sales.
People buy new devices, because they are doing a new deployment, or replacing faulty devices, or upgrading/expanding existing deployment.
In upgrade/expand scenarios of old deployments, customers might try another brand for access points. If it's gonna break compatibility, then one might as well just go to different vendor.
In replace scenario. It depends if one wants to be investing in legacy system, that is incompatible with new generation of models. So, one might go with upgrade/expand scenario here, as well.
In new deployments. It varies, if one needs outdoors coverage immediately, then it's going straight for a different brand of access points.
With this move, MikroTik removed compatibility-breakage reason to try/switch to other brand in all above scenarios.
It is also strategically a good move, because long term interest in brand requires a trust. In case of networking one wants to trust, that future new devices will be compatible with old ones, or old ones will be brought up to date to be compatible with new ones - on software level. In case of 802.11r/k/v it's more important, because there's (AFAIK) no vendor-agnostic standard for multi-AP cooperation.
I believe, many people waited on what happens next. Or, went with other brand already. I.e., now - after this move, I will purchase another wAP ac once winter passes in order to complete the coverage of my garden.
Additionally, it shows, that MikroTik cares about users. And, rather makes things better over time, than going with "planned obsolescence" approach to force new sales. I love this move.