No toy company has ever sufficiently milked even the ubiquitous T2 license let alone The Terminator or T3.
Lets see -
Kenner: mostly non-canon toys so lets disregard
McFarlane: MM4 T2 T-800, MM4 T2 T-1000, MMV T2 Endoskeleton (plus 2 useless variants), MMV T2 Sarah connor (3 headsculpts), T3 T-850 (1 or 2 variants), T3 T-850 w/coffin (1 or 2 variants), T3 T-X, T3 T-X endoskeleton, T3 boxset with T-X endo and BD T-850
NECA: Cult Classics T2 Endoskeleton
Sideshow 1/6th: T2 T-800 (plus exclusive with rosebox), T2 T-1000 (plus exclusive with wrenching arms), T2 Sarah Connor (plus exclusive with cap)
Hot Toys 1/6th: T1 T-800 (no likeness), T1 Kyle Reese (mild likeness at best), T2 Endoskeleton, T2 Endoskeleton BD paintjob
Why have we not seen Hot toys try the T2 T-800 and T-1000 and their various outfit changes and states of battle damage? They would undoubtedly do a better job than Sideshow did. Why can't anyone get both the T1 license and actor licenses for that film and get us Tech noir T-800 and 1984 Kyle Reese? Are we ever going to see the iconic T-800 on Harley or the T-1000 on police bike in any scale? A fully BD T2 T-800? So many missed opportunities.
Anyway, as to T4 - I think I'd probably end up buying anything Hot toys made particularly the T-600.