There's no reason the App Store can't hang around, we just want the ability to sideload. Comparing it to not wearing a seatbelt is a straw man, as it's more like being able to use your car however you like without the manufacturer's say so.
I agree with your desire to side-load. My only caveat I would apply to that is to put some super really scary warnings to the user (as they will be no longer within the security of the walled ecosystem). I don't want users to accidentally side-load something because someone told them to, and not be aware of the extra risk the are potentially introducing.
There's a limitation on the number of apps you can sideload (3), and each app auto-expires after a short period (7 days) of time and needs to be re-provisioned.