I'm not a full time collector. it's an occasional hobby for me. so excuse my ignorance here.
Wouldn't a worldwide release cause issues with how the sets are divided up when they hit western markets. I like the idea of worldwide releases, but wouldn't it be a logistical nightmare.
I haven't bothered completing a set since xy days. I've noticed with the most recent sets that the western releases have included significantly more cards than the japanese equivalent. e.g. unified minds had 258 cards the japenese set it was based on only had 115. to make such a large set they've been drawing heavily from japenese sub sets.
them needing 50-100 extra cards for a set is a relatively new thing right ?
200+ cards seems to be what they want for western sets now. With this being the first new gen of cards that's required such a large number, we'll certainly see something different. You said that Japan is skipping their usual jan subset, so what if to avoid delaying the western release, they bolster the numbers of the first sword & shield set numbers, by taking cards from a japanese subset from sun and moon that never came west.
they don't change the western card format (as in the card design) every gen. e.g. black and white set cards had the same design as X&Y. So it's likely the base card design in sword and shield is identical to that of sun and moon. So theoretically they could pass off a previous gen card as a new gen card. & bolster the set that way.