Apple is taking care of notifications number displayed at once in the screen. They call it grouped notifications. You don’t cover it on your article.
Apple’s solution for me solves this problem well and keeps the idea of timeline alive.
Since I’m always with my phone on hands, and I’m pretty sure this is the reality of most part of people, I’m up to date with the notifications I’m receiving. What really matters to me is the last notifications. With your solution I’m a little bit lost on which was the last notification and where it will be placed.