It's interesting to think about various aspects of marketing the models, with ChatGPT going the "internal router" direction due to address the complexity of choosing. I'd never considered something smaller than Haiku to be needed, but I also rarely used Haiku in the first place...
If you're going smaller than Haiku, you might be at the point of using various cheap open models already. The small model would need some good killer features to justify the margins.