1. cloud based/harvesting as much data as possible and/or 2. subscriptions
I prefer apps like for example Omnifocus [1], that give you:
1. the ability to client-side encrypt your data so your data won't be sold/misused, and 2. instead of making profit of selling your data, simply let you pay a larger amount upfront for it instead. Thus, you also know exactly what features you're paying for - as opposed to subscriptions...
[1] https://itunes.apple.com/us/app/omnifocus-3/id1346190318?mt=...