Whatever method it is, it will probably defeat the purpose of ending unsigned side loading. Whatever the hoops are, users will be trained to jump through them.
This is sadly true. They're going to attempt to throw up a lot of warning dialogs to dissuade users, but we know from long experience that users will click through anything to get to cat videos.
This is actually not a change, really, since they were already going to leave sideloading via ADB open, so their plan already included an "advanced user option" which users could be trained to do. This new thing must presumably be easier than ADB. My guess is that it will feature more scary warnings than enabling ADB, but will allow sideloading without using a USB cable to connect to another computer so that on balance it will be approximately as hard.
During another discussion of this I posted a story that an Android OEM related to me when I worked on Android security, when they asked me when we were going to "close the USB vulnerability", i.e. disable ADB.