A no-longer-exclusive App Store might tighten its rules and become more opinionated. It might even be more willing to reject shady developers, blast scam apps, and decline certain types of apps altogether. Apple acts as if today’s App Store is just curating the platform, but it’s not–it’s judge, jury, and executioner. If you can fall back on telling developers to release their apps on their own, it’s easier to be a curator.
This is an interesting take on side-loading, and whether you agree or disagree with it, I think it does point out the inherent friction in being the platform holder, being a competitor on that platform, and being the sole arbiter of what gets to happen on that platform.
Think about the Apple Store itself. Apple sells a bunch of third party products in their stores, and you can be pretty damn sure that anything you buy from the Apple Store, Apple-made or not, is going to be high quality because Apple curates the products they sell there. Apple can curate their stores because if they don't think an accessory meets their standards or just doesn't vibe with what they want to promote, that accessory-maker can go to Best Buy, Amazon, sell directly to consumers, or hundreds of other options and they can still have a successful business.
However, if every product that worked with Apple device had to be sold in the Apple Store, the Apple Store would become a less curated place and would be flooded with things that Apple may not love, but has to display anyway. This is the reality of the App Store today, and I think it worked great in the early days, but as time moves on it's becoming problematic for everyone involved; Apple must list apps they know are bad, but technically can exist, resulting in poor experiences served up by Apple's store to users, and developers are hamstrung in what they can do/say because their entirely livelihoods are dependent on Apple allowing them to continue doing business in their store.