I often support open-source projects financially and I would be a lot less likely to support this now that it's not. It's not just a matter of giving anything for free. It's about continity: That someone else can carry on with the app (and the data I've put in it!) if he decides to give up on it.
But like I said I don't like this particular app anyway for the reasons I mentioned so I don't use it. It would however be a big detractor for me when looking for a new app.
Especially this thing would put me off: "I've decided to figure out how to make it sustainable first before figuring out potentially how to license it, in order to make this less risky for me."
So in other words, there will be monetisation coming later, but no indication on what kind of price or payment model (think monthly, lifetime etc) he will go for. This would be a big uncertainty for me if I were to consider spending time to put my data into this thing. Who knows if I'll find the upcoming price acceptable. This and the continuity thing would make it a non-starter for me, and I assume many others too. Don't forget the market of notetaking apps is very crowded.