I would guess that it is gone for good. Have no proof, have no insight.
But, everybody on this post complained that it only had a 1000 lb tongue weight rating. I am guessing that the new ones will end up with slightly more payload, that would allow max towing in the 9000 lb range with a similar tongue weight rating.
I had alerted this dropping of the 2500 for 2014 a couple months ago when GM published the 2014 order guide.
I also agree with the linked article that the 4.3 will probably be an option (or standard). The 4.3 feels and acts just like the current 5.3. For most non-towing users of the Suburban, it will improve fuel economy yet still allow a large SUV.