I just got two CASNext certificates four days ago. My certificates still show the Terms & Conditions that say you must book & complete sailing within one year. I would love if they do not expire, but I haven't seen anything that would suggest such a change.
My certificates also say you can use two if it meets criteria for DoubleUp, and three if it meets criteria during a TripleUp promo. It specifically says you can't use with CruiseNext. Again, it would be great if T&Cs are changing for CASNext, but I wasn't told anything different.