One of the problems with any admin template (as shown by a plethora of ideas) is that there is more that one way to achieve most things.
For instance, I would like to have a dashboard centred round content from the authors perspective, where as others would prefer it to have more admin type information.
I like to use tabs for content forms, others prefer sliders or everything on one view.
The ideal layout for a large screen is not necessarily the ideal for a mobile - even with moving divs under each other.
With the current Joomla admin template, customising bits of it for the ordinary admin feels like a nightmare waiting to happen.
So, will the new generation of admin template be easier and safer to customise? Will the admin be able to create overrides that change the layout of parts of the admin UI relatively easily? Can third party developers create installable overrides that, perhaps, offer alternatives to just parts of the template without having to commit to having everything changed?
Being able to make small changes to just a bit of the template without breaking the system may be attractive to many admins who are trying to get the UI to fit their clients needs.