I'm still waiting for the design space teased with Chains of Mephistopheles and Notion Thief to be fully tapped into. That beyond the simple can't be countered/protection from blue there are more creative and color specific ways of hating on blue (or other colors really). Cards that weaken the enemies color's strengths, and force them to fight their game. Thalia does a really good job at this. She's a weenie, and punishes anybody else not also playing weenies, and turns the game into one that's advantageous to white.
I feel like red and green have the most untapped potential as they have the largest gaps in design space. And it seems totally natural to have these colors, who know they will outright lose to blue control, develop can't be countered stuff, but also develop weapons to force blue to play a red/green game, where blue can't properly compete.
That's why Notion Thief bothered me so much, a perfect example of a car that punishes blue's mains strength, and they print it in blue.