> we don't need anything near Opus to be productive. Sonnet is plenty productive enough

For niche applications, sure. For general use, I think the tendency towards the best model being used for everything will–to the model publishers' delight–continue. It's just much easier to get a feel for Opus and then do everything with it, versus switch back and forth and keep track of how Haiku came up with novel ways to dumbfuck this Sunday evening.