Is this a possibility? Or would Artisan and Warners have to join forces and is that likely? I love those bonus disks of extras that sometimes come with movie trilogies.

MGM, Artisan, and Warner would have to join forces. Doubt it would happen, and there's not much to be added to the first two, with the 3 DVD releases of Terminator 2, thus far. And the first is already an SE.

There is a T1 and T2 box set (which includes Terminator SE and Ultimate Edition of T2) available outside Region 1



EDIT: I do not think we will see a boxed set anywhere with T3 in it, because the rights are in the hands of Sony for Europe and am not sure about home video rights.

UE on R2 has only the theatrical release and the extra scenes as deleted scenes (ie no seamless branching)