(a) Linear timeline.
(b) Stop injecting stuff into people's timelines.
(c) Hide like and retweet counts from anyone but the person who made the tweet.
(d) Add a cooldown period on tweets: they're not visible for this period, and they can still be edited during it. Editing a tweet resets the cooldown period.
The problem with all this is that it drives down "engagement".
Addendum:
(e) Make it possible to prevent retweets (including quote retweets) from certain accounts you follow from showing up on your timeline. There are certain people you might like who retweet effluent, and you don't want that effluent going straight into your eyeballs.