A format with so many restrictions on search is gonna be weird, I hope it doesn't just make the types with dedicated search dominate. We'll have cherish ball, Elm's, and pokecomm at least but I've heard bad things from people who tested post-rotation.
Right now my hunch is that strong decks that have type-specific search power are going to excel, so things like Electromagnetic Radar, Mysterious Treasure, and Net Ball.
Looking at all of our options right now, I'm thinking that Pikachu & Zekrom GX decks are going to excel the most immediately after rotation. Electromagnetic Radar is probably the best search power item in the game after rotation. It does a few things for the deck that no other deck can touch:
1. Lillie was one of the best supporter cards partially due to Ultra Ball -> Lele -> Lillie, and the discard 2 from Ultra Ball is great hand thinning to make Lillie dig deeper. This was something every deck could universally access, but now this isn't going to be a thing everyone can do.
2. The card is generally better than Ultra Ball for any electric GX-focused deck due to it being a search 2 GX instead of search 1.
3. Dedenne GX just so happens to work out brilliantly as the next best bench warmer Pokemon that can conveniently be grabbed by Radar as well. Between Zeraora GX, Pikachu & Zekrom GX, and Dedenne GX, you have a lot of selection from a single card.
On top of that, Electric decks have a lot going for them.
1. Fighting/Rock type basically doesn't exist immediately after rotation in a meta viable form, so there is no concern for weakness.
2. Zeraora GX offering free retreat means that even when Great Catcher comes out, people can't just move Pokemon up into the active to get you stuck on massive retreat costs.
3. With Choice Band gone, Charizard & Reshiram GX can't OHKO you with the first attack anymore. On the contrary, Electropower is now basically the only potent damage increasing source.
4. Thunder Mountain Prism Star is a thing.
So yeah, basically a long winded way of saying that I agree with you. But then again metas are usually predominated by 3-4 major decks anyway, so it's not like that fundamental concept is really changing. I'm only ever particularly concerned when "Tier 0" metas are generated.