I enjoyed your article. I will point out that the "box" naming scheme likely predates the Pokémon TCG. It is short for "toolbox" and refers to decks that run a wide variety of cards allowing them to address the situation with the correct "tool" (not Pokémon Tool, but card). I also noticed that if we wanted, we could start a theme for naming these decks: Blue Box, Black Box, Blitz Box...
Seriously though, it was a nice, on point article. A lot of us were cautious optimistic (or reservedly pessimistic if you're worried about game balance) with Max Elixir; Dark Patch taught us that attaching to the Bench did not guarantee a slow open, and you just explained clearly how many Types are making use of it now... even alongside other Energy acceleration (which I know I did not see coming).
With the forthcoming rotation, Seismitoad EX's Quaking Punch and Trevenant's Forest Curse will both no longer plague Standard format play. So, I'm actually expecting to see a noted increase in Max Elixir (as well as Mega Turbo) play to provide energy-attachment acceleration in many decks. Getting 2-3 extra energy into play T1 or T2 can make a significant difference.
Aye, though to my surprise I just got some push back when I suggested it for some decks. One valid concern is that without Battle Compressor, these two aren't going to be as effective: kind of obvious for Mega Turbo, but thinning the deck really helps Max Elixir as well. I think we've got enough alternatives to keep it a real possibility though.
I wonder if part of it is people are so used to how thing are that it is easy to forget post rotation, things aren't just going to be different, but a lot of tricks that wouldn't work well enough before get a chance to shine. I mean, I don't expect slow, steady Stage 2 decks to become the norm or any radical shift like that, but the two forms of Energy acceleration you mentioned, plus perhaps Exp. Share, are looking better and better to me. Theorymon on my part, so please take that with a sizable grain of salt.
Max Elixir started to become more common as decks moved more towards basic energies an a larger energy pool that peviously. With ten to twelve energies the odds become rather favorable to hit one of them with Max Elixir. I also assume that some underused tools such as Exp. Share will become more relevant. It is a vital part in Xerneas BREAK decks in addition to Max Elixir to hit number on the second to third turn with the Break evolution. I believe that the new format will be the time to shine for fairies.