More than anything, we need NEW cards that combat the two primary power centers of Vintage: blue Xerox and Shops w/tax effects. Damping Sphere in Dominaria appears to have been a valiant, but comically-bad attempt at that. I seriously wonder what genius said to themselves, "This will stop Xerox AND Shops."
Wizards needs to print cards in B/R/G that counteract the dominance of Shops and Xerox (I exclude White because it already has most of the hate bears and functions as a lesser-Shops with less vulnerability to artifact removal).
We need Root Maze on a (cheap, not the 3cmc Thalia) creature. We need Naturalize as a Channel ability on a card. We need cards that come out early to hamper Xerox (cheap, not the 3cmc Leovold). A red creature that makes instants and sorceries cost 1 more. A green creature that makes artifacts cost 1 more (tax the tax deck). A black card that does something else Vintage-relevant, like 1cmc spells cost 1 more (weird, but maybe it would work). If they can print Cage to nerf Dredge and Oath (in a surprisingly flavorful way), they can spend a few slots on cards to hit the two strongest engines of Vintage.
At this stage of the game, every color should have tier-1.5 card selection and counter (in a color-appropriate flavor). There should be a green "Force of Wildness" that pitches like FoW to counter artifacts or enchantments, for example. A black instant that says, "For each card target player would draw this turn, they must discard a card or sacrifice a permanent instead."
Blue can be the best at selection and counter, but the other colors shouldn't be cut off entirely. Blue has been given the best cards and then has fetch/duals to splash their win conditions (Mentor, Oath/creature, Tinker/Blightsteel, Tendrils, etc.). The only reliable counterbalance has been a broken land and all the tax effects that are fit to print. Ravagers Shops has the challenge of its ability to anything in response to removal, but if you could afford to cast more than one removal spell in a given turn (due to tax effects) you might have a shot.
I'll stop there for now, since I have to go to work in the morning.