I don't think Shaymin-EX will get banned.
FIGHT!
They don't normally, if ever, ban cards for making the format too fast.
Up to this point, they haven't. Almost all of Pokemon's consistency has been in the form of once-per-turn Supporters, or requiring a massive setup (multiple Zoroark-GX). Shaymin-EX has been sort of weird in Expanded, it's been ok. It's helped combo decks do their combo thing more consistently, but it's come to a head that can't be ignored anymore.
In the end, it all depends on how fast they want their format to be. EVEN IF Shaymin-EX is banned, give it like 5 sets from now and we'll just be back here with maybe say, a Lumineon V that while is much needed in standard for the speed it brings, would be """"busted"""" in expanded due to it's speed, especially when combined with X card. So then they'll ban that, or no, would they ban the card that "makes it busted"?
Then we can address that problem 5 sets from now. In an ever growing format, banlists will always get bigger. I mean, look at Yugioh.
Nobody had complaints about Shaymin-EX before Scoop Up Net, just saying.
There were complaints. Lots and lots of complaints. Look back last season at Zoro-Exodia. It was one of several cards pointed at as being a problem. Red Card and Delinquent were deemed the bigger problems at that time.
I don't think either card deserves a ban, since I think currently their only thing with bans is "do you at least get 1 turn to play the deck?" and NO, donk shouldn't be included in this. Even then, I still honestly feel banning Latios-EX or Pheromosa-GX works better. But the reason why I'm saying don't include donk when talking about Shaymin-EX/Scoop Up Net ban is because it's not exactly unviable, but definitely not a deck I'd ever bring to a bigger tournament, unless I'm expecting like ONLY Roweggs or something. Sure in bo1s this deck rocks, but since when will they ban a card for not being fun to play with with your friendos, lol.
Another thing to think about. A lot of the T1 hand lock strategies wouldn't be NEARLY as good without Shaymin-EX. Not to say you couldn't do it, but definitely not as good as they were.
TrevNoir hand lock got Top 8 at Dallas. And Turbo Dark was THE DECK to run for the event and looked like it would destroy TrevNoir effortlessly. And TrevNoir got Top 8. When SwSh came out, it was still one of the top decks to run. Now it's one of the only 2 decks you can run. The only thing it has in common with Turbo Donk: Shaymin-EX and Net. Without Shaymin, Net isn't Broken. There isn't a single deck that becomes busted and will dominate the meta in the same fashion as TrevNoir hand lock if Net stays unbanned.
Additionally, Zoro Exodia was a "second turn hand lock" and that deck got destroyed by the banlist.
And now with Crobat V, "Shaymin #5", the combo gets an ever bigger consistency boost if left untouched. Even if you banned Net, you could still use Super Scoop Up and the 1-of Scoop Up Cyclone (if you aren't already). The combo will still be viable.
But honestly, Milotic will more than likely get a ban as well (as it's Ability lends to the idea that it was never expected to be used outside of EX-era).
Multiple things will get hit, but Shaymin-EX is almost a shoe in.