Edit: My question may not have been clear: so I'll rephrase: I'm asking: is there a way to update my app through the App Store (continue to push updates to users) if I decide to stop selling my app?
Original question: I'm a mac dev assessing whether I want to sell my app through the App Store.
One question I had was, if I ever decide to stop selling through the store, will I still be able to issue app software updates to the initial users who downloaded the app.
Hopefully this is an easy YES. This seems important to me because if the answer is NO, then Apple's kind of locking the dev in to keep selling the app.
Define "stop selling the app". Meaning you are offering it for free, or pulling it from sale in the App Store?
If you are offering it as FREE, then YES, you can still issue updates to new and existing users.
If you pull the app from the App Store by "Remove from Sale", then NO, your app will not appear in the App Store, and the same goes for updates, you will not be able to push any new updates until it becomes available in the store again.
Apple does not want you to offer your app outside of the App Store. Back in the day you could provide it as an unsigned developer binary and Mac OS would complain, but allow you to install. Apple is now making it harder if not soon impossible to do this.