Since a triple monitor configuration is a de facto standard for pro users, pro configurations, etc., I would disagree with your characterization of "three 4k" as being "amazing".
I would characterize it as the absolute bare minimum to even be in this space.
I have 5 monitors attached to my 2009 pro (3x 2560x1600 main displays, a 1920x1200 offset on the wall, and a 1920x1080 "tv" cabled out to another room) and I've considered adding a sixth.
It's hard to say how many <4k displays you can add to the ports on the back in addition to the three primary 4k displays, but it had better be more than "zero".
Are you disputing "amazing"-ness of 3 displays, or number of horizontal lines of resolution? Because I calculate your collection of displays at 7.08k, and 3 * 4k ~ 12k, or a 70% increase over your current count.
I would characterize it as the absolute bare minimum to even be in this space.
I have 5 monitors attached to my 2009 pro (3x 2560x1600 main displays, a 1920x1200 offset on the wall, and a 1920x1080 "tv" cabled out to another room) and I've considered adding a sixth.
It's hard to say how many <4k displays you can add to the ports on the back in addition to the three primary 4k displays, but it had better be more than "zero".