The track would have to be able to accept the new shifting forces.
Therein lies the rub.
The 7DC track looks like it is massively reinforced to allow for the side to side motion, the RSR ride vehicles have something like north of 20 wheels underneath the track in various positions to keep the ride vehicle on the track, and that is because of speed, and unwanted side to side motion, and other unwanted movement, and the forces that accompany that.
What I remember from the old Matterhorn was the vertical dropping sensation, which probably was accented because of the loose seat-belt and the open bobsled. The new rider position with legs looped under the chair (if I got this description correctly), looks like it was introduced to prevent the upward/vertical movement of the rider independent of the ride vehicle. Remember the sad accident of the woman who "stood up" on the Mattehorn, they obviously want to keep riders firmly inside the vehicle. The old ride configuration definitely provided some thrills as you felt the bobsled almost drop out from under you.
Retrofitting the ride so that you've got a ride vehicle that moves indenpedent of the chasis to some extent would probably require reinforcing the track, and decreasing the banking angle as the ride vehicle would bank for you.
I think an improvement might be to build bobsleds with individual seats inclined backwards more, which if they all inclined at the same angle, you'd be able to the fit the same number, and you'd have more leg room. When the bobsled shoots down, and your momentum carries you forward, you might get a sensation of "lift" as not all of your weight would be on your tail-bone, but spread out over a larger area, and your feet and head would sort of go "airborne" for a couple seconds. But, then again, if you incline the seats back too much then people have trouble getting inside.
For some sections of the 7DC track, it looks like the rails vary with the parallel to the ground, introducing some "shaking" of the ride vehicle like in a mine. Basically, for example, the right rail dips, and the left rail stays parallel to the ground, and this introduces some "swinging" to the ride vehicle.
Similar style vehicle on Matterhorn probably couldn't have such a rail configuration given the speed, it might cause passenger to slam against the wall of the ride vehicle.
If you watch the winter Olympics, when the bobsleds start swinging horizontally like that, they soon crash!