I needed to call in to get a plan change started immediately, instead of the next billing cycle and played dumb asking if the the $50 NE2 discount really was gone. The rep replied that it was taken away April 15th, yada, yada but if you place the order with a customer service rep, they still have the option to apply the discount and yes, it can be applied to a pre-order. The CS reps only have the option until May 15th and it must be done over the phone. Thought this might help out, especially for the people transferring and/or doing alternative upgrades.
Here's a screenshot of the confirmation email (pre-order of S4)
Here's a screenshot of the confirmation email (pre-order of S4)