I would really like to see the introduction of notification grouping, and I will give some ideas for this
I often come to my notifications to find 10 notifications for the same conversation thread
in my email i would have a threaded email
in Monday I have a separate notification to open for each
I think that if there is 10 notifications or a for that matter more than 1 for one update they can show as a stack, clicking it expands the stack or you enter it like a group, you can then mark all as read for that stack, delete etc, after all i click one, i read the discussions and now i have in my current example 18 more to mark as read to keep my notifications clean and organised.
I also think that on a board level you could have a notification Icon for anything relating to that board, then if you visit that board you can go through the board notifications and clearing them/reading them here will mark them as read in the master notifications panel
Any questions about my idea let me know