such and interesting discussion and one that has me scratching my head!
I've just drowned my MBP, and someone in another thread, suggested getting a powerful replacement, but using it in a dock (clamshell) to replace my ageing iMac, as this will mean only having to buy one capable machine. Solid Theory, but when it comes to a monitor you're totally screwed, you either have to bite the bullet and buy a very expensive Studio display, or settle for a less than perfect third-party solution. I believe this is why professionals like myself, always went for the 27" iMac, as you could run an inferior monitor next to it for pallets and emails – a perfect set up. So the 27" in their range is going to be very much missed.
For myself, this is where my head scratching starts... there really is no simple (or cost-effective) way for me to upgrade. I could get a 14" MBP, with 32GB UM and 1TB SSD, but i'll most likley have to drop another £1500 on a monitor. If I go the Apple strategy it will be a Mac studio and Studio monitor but i'll not have the portability, so will still end up having to buy a laptop.
I wasn't planning on upgrading my iMac, but everyone has a plan until they are punched in the face, so i'm aware I might be forced into this sooner rather than later and I don't want to buy now, and end up regretting it in the future...
Currently writing this on a late 2013, 27" which I upgraded last year to run off a fast external SSD.