Really...I know Tamiya did a late '90s GT3..haven't seen a GT2 kitted. I'd like to see and of the current 997 generation 911s kitted...
I'd love to see some current BMWs (M3, M5, M6, 545, etc), Mercs (CLS, SL, S-class, etc), Audis (TT, RS6, S5, etc) kitted... from Japan, I'd love to see the new G37, GT-R, and Prius kitted..
As far as the domestics, at the top of my list would be the '08 CTS (I love the new Caddy, may buy one for next daily driver), followed by the new G8 and the new Bullitt Mustang....I'd also love to see a current Crown Vic, and the '03-04 Marauder kitted, and a current Grand Cherokee (esp. the SRT8).
As far as the oldies go, I'd love to see some subjects that were never kitted before, like a '68-69 Mercury Cyclone, a '69-70 Mercury Marauder, a '70 Plymouth Sport Fury GT, a '67 Pontiac 2+2, '71 Caddy Coupe de Ville, '71 Buick Centurion convertible, '73 Chevelle SS, '73 Buick Gran Sport, '73 Grand Am, '85-86 Mustang GT, '87 Grand Prix 2+2, etc..