That was one of the primary reasons I ended up choosing a 5.7 over the Ecodiesel. I was trading in a 2013 Laramie Longhorn 5.7L to upgrade to a 2014 Laramie Longhorn with the 5.7/8 speed combo.
When the Salesman explained the plug interval changed on the 2014 to 100,000 miles, I had to verify it with the Service Manager. He confirmed it thus the numbers to run a 5.7 became even more attractive. Granted, I don't think I'll leave them in there for the full 100,000 miles as Chevrolet has encountered plenty of problems with plugs snapping off when removed after 100,000 miles, but even if one replaced them at 60,000 or 75,000 miles we're miles ahead of the original 30,000 mile change of the pre-2014 models.