3.5.4 UI on 4.0.1+

I would like to ask for the ability to switch to the 3.5.4 UI on 4.0.x and any newer versions of TVAI. Alternatively, I would like to ask for newer models to continue to be supported on 3.5.4, whether that require special “compatibility” versions of the models to be released, or if 3.5.4 can just pull from a special model repository.