Basically all modern fighters since the 1980s are aerodynamically unstable and require a computer to fly. A collision like this is almost certainly going to do major damage to the airframe (screwing up its aerodynamics) and maybe flight controls as well. I suspect the plane will be well outside the parameters that the flight controls software can deal with, making stable flight impossible.

Depending on how much damage was incurred during contact, since they were already flying predominantly the same direction & speed, at a higher altitude they might have uncoupled and regained controlled flight. Examples of more grievously damaged airplanes have landed in the past. I don't think they had any real hope if they stayed joined, tho.