I unfortunately can't see this working in every scenario. For a Switch it seems like a workable solution as the owner's motivation is the only controlling factor in whether or not the device stays on the secure side or the anything-goes side. (If there are loss-leading/cost changes to the hardware that is a discussion that can be addressed separately.)
For a device like a phone the owner's motivations can become muted, such as by a service provider functionality requirements or an employer's desires. This is similarly where the problem comes about in the discussion about side-loading.
We already know that there are many developers who wish to live on the 'nasty' side, but there is also a laziness motivation in using that side as well, it's less work for the developer.
This then becomes the ever-widening hole where consumers get brought onto the 'nasty' side blindly because that's where the market is - at the same time exposing the users to all of the 'nasty' stuff that technology was originally there to protect them from.
For a device like a phone the owner's motivations can become muted, such as by a service provider functionality requirements or an employer's desires. This is similarly where the problem comes about in the discussion about side-loading.
We already know that there are many developers who wish to live on the 'nasty' side, but there is also a laziness motivation in using that side as well, it's less work for the developer.
This then becomes the ever-widening hole where consumers get brought onto the 'nasty' side blindly because that's where the market is - at the same time exposing the users to all of the 'nasty' stuff that technology was originally there to protect them from.