Current line of scrimmage situation is the worst case scenario. Linemen are a couple feet away from each other and they start from a crouched position. They explode up and hit the opposing line, very often with their helmet/crown, down after down, 60-70 times a game. You could not plan a better way to get CTE.
1) Neutral zone at the line, they start 2 yards away from each other.
2) Have to start from standing position, and/or:
3) First contact has to be arms
It would be a bit of an adjustment like it was for dynamic kickoff. You're never going to stop all head trauma in a contact sport but the mechanics of the line positions are basically designed for it.
Or would the center be at the ball and do a short long snap to the backfield?
What would be considered a "standing position"? I guess both feet on the ground, can't use hands or arms to brace against the ground or self.
There are some side effects (goodbye tush push) but it drastically reduces helmet contact for those 8-10 players every down.
And indeed, disallowing brace against ground is all you'd need to get the standing result.
The game would change but I don't think it would be existential, more of an evolution. It may even make it more fun to watch. Speed becomes much more important as does general athleticism.