1. Real-time financially valuable tweets from experts (market analysts, crypto experts, breaking news that can move stock markets, etc.), where the tweets are perceived as genuinely worth paying for
2. Supporting creative types -- musicians, comedians, etc. -- not necessarily for the tweets themselves, but just to support them because you like them, and maybe you'll get early access to show tickets too or something
3. Paying for content that's genuinely interesting in itself, e.g. short newsletters in tweet form.
I'm not sure the price is high enough for #1 to be a viable business model. I'm not sure enough people will voluntarily pay #2 to make a dent (or they already use Patreon instead). And #3 seems particularly ill-suited to Twitter's short-form.
But we'll see -- it would be nice if this did wind up supporting people financially.