I think you said yourself: it’s a UX nightmare. I don’t think it’s going to matter if the timeline stays in chronological order, or algorithmically altered, if the general UX sucks.
I’m one of those power users and I have FOMO when it comes to Twitter. But thankfully, there’s “While you were away..” and “Highlights” to help me catchup with important events that I’ve missed throughout the course of the day/hours.
Do I need to see 90% of the important tweets? No. All I need is one tweet and I can follow the (hash)tag or check the news from there. If I need to know a certain topic, for whatever reason, I would create a list with people who are close to that topic. I follow the NFL and even though I don’t follow 90% of the tweets, I have a list that allows me to check what’s happening in that sport. Need to check news about tech? Create a list of tech peeps in your circle of interest.
Twitter already has these features that makes it easy to follow topics and people of interest to you. And they’re everywhere. An algorithmic timeline is a yet-another-feature that gets thrown in that set-of-already-useful features that people don’t really need to improve the experience. What they need is find a way to make the UX better without throwing another feature that hopefully sticks.
That or just use Facebook.