I actually like the basic energy argument. While it's obvious that we wouldn't rotate basic energy, there has always been basic energy in the format. While that could obviously and easily change, it's very plausible that no new basic energy has been printed because there won't be a rotation.
My current thoughts lead me to believe no rotation because all the rotations seem really weird and would get rid of very basic cards (heck, if we rotate just NXD-on we lost Energy Switch, Super Rod, Energy Retreival, etc.). Anything past NXD-on and we lose a ton of search cards along with Prism and DCE, two cards that seem unlikely to leave the format for various reasons. It's very possible that there could be a NXD-on rotation, but based on the current outlook, no rotation seems to be the most likely (although personally I would love to see a DRX-on format because it would open the doors for a huge amount of creativity, and a format without catcher would be really interesting.)