Axoloti Control is still in dev (afaik) .. the last prototype is great. I think pretty close to final hardware form, but some work still needed on firmware (but its working) - but ive no idea on release plans/dates
( bare in mind, it requires both hardware and software development)
yes, Axoloti Control will be complimentary to custom controllers, its connected a dedicated set of pins. x4 (iirc) via a ribbon cable... and uses spi (again iirc)
I think, even for those that have developed their own controllers, it will still be very attractive addition... due to the close tie in with the parameters system , and other 'features'
some will still want custom controllers, e.g. because they want lots of dedicated pots/sliders, but for more generic control its going to be perfect.
so definitely a role for both.