If it starts out not requiring any internet connection, and you never update it, it won't get any more restrictive.
If I recall, there have been PS3 games that required an update to function, and contained that update on disc. So you could reach a point where you can't play any new games without updating.
No one would force you to install those updates, so technically you're right. But I would consider it just as system killing as forcing an update over the Net.