I think most seem to forget the existence of the plastic figures...
Mk7 is pretty well represented now: original plastic figure, battle damaged version plastic figure, white "sub zero" version plastic figure, black "stealth" version plastic figure, the diecast figure which doubles as pod mode, the open armour diorama piece version that recently released, the black and gold chrome diecast figure, the D100 red and silver diecast figure and the new suit up version that just released. Oh, and the Venomised Iron Man is the mk7 (did I miss any?).
Add to those the mk21 Midas since it is just mk7 in gold then there is the original plastic figure, the Shanghai chrome version plastic figure and more recently the diecast figure.
If you want to include other brands then there is also the Play Imaginative mk7 diecast figure, the Play Imaginative gold mk7 diecast figure and the Play Imaginative "raw" unpainted silver/grey diecast figure plus also another brands take on the open suit mk7 (though I forget the brand, some Chinese third party IIRC). Oh, and Crazy toys/Empire Toys recast the original mk7 to create a semi jointed statue. You could technically count the Kotobukiya statue too since it is 1:6.
Crazy thing is I own/have ordered almost all of the above. I am only missing the HT D100 version, HT Venomised mk7, the Kotobukiya statue and that third party open suit version. I even have that funky cheap "Apple Iphone" mk7 figure. Love that crappy KO. I think it was an upscaled recast of the Hasbro 10 inch figure. I found one in camo scheme and another in Iron Patriot colour scheme too IIRC though I think I repainted one gold.
I can't imagine what HT would improve if they were to do another mk7. Make it even taller???? Add "Neon Tech" paint scheme? Do a "hologram" version?