At first I thought the concept of a notch was a bad idea. Then, the more I thought about it the more I liked it. I don't know whether the new MacBooks will have a notch, but I now hope that they do and I can even see this coming to the iMac in the future.
There are, however, a few user interface issues. First, they can't allow a simple mouse over or move to enter into the notched area. There should be a virtual top of screen that will align with the normal menu bar so that any mouse gesture toward the top ends up just as it would today, stopped at the top of the menu bar.
So, they will need to implement some kind of modifier key or special mouse action to enable the user to move into the notch area on either side of the camera (if they want to, otherwise mouse behavior and menus would be exactly as they are today). Then, if the user commands to enter the notch area it might even be possible that a drop-down area will appear to cover the normal menu bar which would also allow more room to display items/information. But, once the user moves out of this area with their mouse the normal menu bar will reappear.
As for items that could be placed in the notch, those would likely be system functions like date/time, user name, keyboard selection, sound volume, network/WiFi status, and notifications -- basically everything that currently appears on the far right side of the standard menu bar of today. There would also probably be room to show more specific notification text or reminders (like telling you that you have a meeting scheduled in another ten minutes).
The dimming of the notch area would have to be under the control of the system. It would automatically be blocked out whenever an app requests full screen, so movies would play full screen (but not into the area of the notch, the display area for all apps will still be a perfect rectangle). Not sure what they might do with this area when the system is in sleep mode, but it might remain illuminated to display status and notifications (an option that could be turned on or off by the user).
I think Apple could make this work and it's probably a feature that would be very difficult for anyone else since you really have to control both the hardware and the software to make this work.
So, I'm now a definite "thumbs up" for the notch.