I feel a lot of us are excited for the AXE16000 releasing, however as we all know it's going to be a very expensive router. The most important thing is, this router will likely have some issues for 3-6 months, until software updates smooth some things out. So if you're looking for a router to just perform right off the bat. I honestly suggest staying away from it, until things mature some with the software.
As for Merlin's support, that answer will come when he decides to speak on it. I do think there's a good chance he does support it, as he has started supporting a couple of Asus's GT routers. I think the biggest thing will be, Asus sending Merlin one of them, so he can add his support for it. Which I feel there's a good chance Asus supplies Merlin with this router, if he wants to support it. As I'm guessing they sent him ZenWiFi Pro XT12, that he recently added support for, and that's a costly product itself.
Overall for everyone on the fence about getting the AXE16000. I would just suggest waiting a bit, then decide. Unless you just got money to spend, and don't care if you have to wait a few months for the software to mature. Which in my case, is something I'm willing to do. I don't mind giving it some time, and I have a backup router I can use if needed for a few months. Ultimately once this router has had several months to mature with its software, if there's still big issues, I will return it, and look at something else.