I think that's nothing more than a pipe dream. It seems that Twitter is bordering dysfunctional internally and is hemorrhaging money at the worst possible time (massive debts to support, slowing economy, less accessible loans). I think Twitter's current strategy is desperately trying to make money and stop the losses.
Many APIs do have price tiers but it depends upon the business model, if the API is the product, or the app is the product and the API drives traffic and use cases. For a super-app, arguably the app is the product & profit generator and an open, free API would support usage of that.