I think the debate would clearer if we had a view of which market segment Apple is going to address because for me it is not clear:
21.5 - Home: Edu, home-office , entry level
27 - Work: more demanding applications (like running microsoft poorly optimised Word, haha) photo, some video, development
iMP - High end work - Research, higher end video, photo and 3D modelling/rendering, ML, development
There is overlap between these segments and the biggest unknown is if the 27 iMac will lean more towards the low end or more to the high end. That will decide how the case will look like.
Personally, I do not think that loosing low end iMP sales to high end iMac configs bothers Apple at all. We should also remember that the processors in the iMP is a year old (or more) and of course can be slower than this autumns processors.
21.5 - Home: Edu, home-office , entry level
27 - Work: more demanding applications (like running microsoft poorly optimised Word, haha) photo, some video, development
iMP - High end work - Research, higher end video, photo and 3D modelling/rendering, ML, development
There is overlap between these segments and the biggest unknown is if the 27 iMac will lean more towards the low end or more to the high end. That will decide how the case will look like.
Personally, I do not think that loosing low end iMP sales to high end iMac configs bothers Apple at all. We should also remember that the processors in the iMP is a year old (or more) and of course can be slower than this autumns processors.