Kyanar: Again, unlikely. Prices didn't suddenly raise on us customers when they got a commercial agreement in place with Chorus for phone numbers, and in fact their pricing to make calls to NZ numbers is still pretty much at the MTR (an whatever the equivalent is called for landlines) already.
(This entire pointless debate is a moot point though - in their response to me they indicated that message volume to NZ is still very moderate, so it's probably not on their short term radar).
FYI Chorus have nothing to do with numbering schemes or voice interconnects. Numbering is all handled by the NAD.
There are a number of providers who simply resell number blocks and connectivlty, and my understanding is Twilio use Symbio networks, who are also the supplier to Skype. The actual numbers themselves are as cheap as chips, so Twilio would incur very minimal costs actually supplying a NZ number.
Unlike foreign SMS the costs to connect directly to 2degrees, Telecom or Vodafone are fixed. They are also big $$$. As stupid as it is, the simple reality is you can't deliver a message to a NZ carrier using one of their interconnects through an approved supplier for less than you can using an international SMS provider. It's fine them all charging well under 1c for sending messages from their own customers, but try and negotiate a commercial agreement and you'll find the price you pay is magnitudes greater.