I see that
Twitter is rolling out some Feed tests [twitter.com]
...working on providing you with an easily accessible way to switch between a timeline of Tweets that are most relevant for you and a timeline of the latest Tweets. You’ll see us test this in the coming weeks.
It seems they want to see how popular their original timeline format is vs. the relevance/suggestions type feed modeled on changes on other Social Media platforms such as FaceBook.
Optional ways to view activity sounds like a good idea.