Yeah, it definitely
is a large set (I'm so excited!
) but I don't really think we can compare it to Legendary Treasures since that was 2 separate Japanese sets (EBB and Legendary Holo) combined into one, and aside from RC specifically containing the Legendary Holo cards I don't see any other connections. And because of the sheer size of this new side set I don't believe it'll be combined with a regular set like Legendary Treasures was because it would be simply
ginormous. It's certainly possible that these cards will end up becoming the special "Generations" boosters in the monthly promo boxes for 2016 like Blui predicted, and that's the most likely estimate I've seen so far.
That said, I don't know anything about Yu-Gi-Oh, so I don't really know what you're getting at there.
I can only compare it to what we've seen with Pokémon and speculate based on that.