Before buying any additional HW, you should familiarize yourself with the options for using it in your network. Regarding OneMesh technology it's worth reading QA section. Pay attention to Q5, Q8 & Q10.

There's a scenario where you can use your already aquired equipment: One AX6000 in Router mode connected by OneMesh with your existing 2 repeaters. Also ethernet cable from the AX6000 router to the second AX6000 AP (second one in AP mode, so you can extend the wireless coverage further in your home). The drawback here is that the second AX6000, which is in AP mode, would not participate in OneMesh network, but still will extend further your wireless coverage (for example configuring the same SSIDs as on the main one).

No, it won't going to give you problems. That's the way you can extend your wireless coverage in there. Just won't let you use OneMesh (it doesn't work between routers).

There's another solution for a big areas to cover, like in your case - using the TP-Link's DECO technology.

For example instead buying a router you can go ahead for DECO system (2 or 3 pack) - for ex. X20 or X60 if you are targeting AX standard.

Configuring the DECO in AP mode (connected to your main router) will give you a better wi-fi experience than the OneMesh IMHO.

Moreover, unlike the OneMesh, DECO supports ethernet back-haul.

As for the TP-Link forthcoming plans, I am not aware, that's up to TP-Link to announce them, if any.

@PK22 

Keep an eye on this list to know when that would be.