I really don't know that it would change SU's zone strategy. Guys are moving farther out to neutralize the zone as it is and occasionally hitting long-range 3s. It would, however, move the easier 3 pt shots a little farther away from the basket, so it might actually help SU slightly.
Good call on the three-point shots. It's the reason that Coach Boeheim claims to play zone at this point--defending the three-pointer. We agree on that. However, I'm thinking about how more distance would potentially pose problems for the interior defense.
In Boeheim's zone, the wing/forwards' responsibility is to guard the offensive wing/corner players as the ball is reversed. If the ball is passed to the wing on his side, a forward defends that until the ball-side guard bumps him to the corner. Then, he guards the corner shooter or short-corner post until the ball is reversed again. If the ball is entered into the high post, though, our center is responsible for that, and the wings are responsible for the post player on their side of the floor (if there is one) or the shooter on their side. If a wing has to cover a post spot in that situation, the guard on that side is responsible for the wing/corner.
That said, here's an example defensive situation: let's say the ball is entered into the high post. If the player receiving it can't make plays from there, no problem. We currently tend to leave that player unguarded or lightly guarded, daring him to shoot or drive from there. I doubt that changes with a pushed-back arc.
On the other hand, if that player is solid from there, the center has to get out on him quickly, the wings have to instantaneously identify whether they are responsible for the post or the wing, and the guards have to be ready to cover their wing areas if the forward on their side is sucked into the post.
Imagine if the offense overloads the ball side with a corner shooter, a slot/wing, and post player. If the ball is passed into the high post (to the weak-side post) and SU's center (Coleman/Lydon) rotates out to guard, it would be very difficult for an Orange forward (say Richardson) to get from his corner responsibility to the low-post player and get inside defensive position. That is a high-low waiting to happen every time. That happens now without the extra space for the forwards to navigate.
Let's say Richardson gets position to deny the high-low. This leaves the corner shooter open. Cooney or G have to rotate to him in a hurry, but having to guard the slot/wing further out will mean more close-out distance to cover. That is a wide-open catch-and-shoot three-pointer or a shot-fake-to-baseline-drive opportunity waiting to happen. In the latter case, we're likely playing 4-on-5 defensively.
If the post and the corner are taken away, who has the ball-side slot/wing? The backside guard does, as he has to rotate over from the elbow area. This player probably has the shortest rotation to cover, but doing so often discombobulates the zone, and he would now have to get out three or so extra feet to challenge a shot. Even if he does, our guards have a long way to recover to their normal spots.
In short, this play, one that some teams currently employ effectively to attack the interior of our zone, would likely be more troubling with the NBA arc. The high ball screen, the quick-reversal-dribble-drive-into-the-seam-from-the-wing, and the screening-the-weak-side-forward/lob-pass-or-skip-pass-to-the-corner-shooter plays would also be harder to defend.
What moving the line back would do is open up more area inside the arc for opponents to make plays. As a result, smart teams would likely force the zone out of whack more than they already do through post entries and dribble drives. Remember the old adage: "Spacing is offense and offense is spacing." I agree we would probably still sell out to disrupt the three-point shots, and players shooting longer shots may miss more. Nevertheless, good shooters already hit NBA-range threes against our defense (as you so correctly pointed out). By setting up their offenses at the NBA arc, opponents would spread our base defense wider. Consequently, the interior defense would likely be more exposed by fundamentally sound, patient teams.
The upside: not every team has the personnel to consistently execute these fundamental plays every season, and even fewer can do it every night.