But I recently discussed my reasoning to go close-source[2]. I've been working night and day (every day) converting 4 cups of coffee into code for the last 4.5 months to create Plume. I don't want to risk not being rewarded sufficiently for it. But, I'm 99% sure that I'll either open source the core block editor or the entire app in the future.
Why withhold the remaining 1%? If you aren't so confident about your decision to open source, there's no need to commit to that decision now.
It's good that you are leaving the door open, but keep in mind that if some folks suddenly become successful with a service that can turn any GitHub repo into a nice looking SaaS, at the click of a button and for a super low fee, I'm pretty sure you'll be hesitant to open source all your hard work so it can harvested.