Pretty much every take I have on this is covered by the discourse here about walled gardens, but I do have two other points of concern: Indexability and SEO.
When you want to view certain content on Twitter, you need to log in. If you don't want to, you're forbidden from viewing that content. If that happens here, I worry that the accessibility of long-form, blog-style content production will lead to more users either being onboarded to Twitter for what should be a simple matter of viewing an HTML + CSS page or otherwise missing out on content that could be valuable to them (e.g. news from prominent personalities, interviews with professionals, press releases from companies, etc.)
My second concern is with SEO. If this really takes off, I worry that a first page of search results that once would have contained articles from a number of separate blogs will become dominated by a single, homogenous site. Perhaps grouping results in the way that Google does could help with that, but I'd rather avoid needing to append "-site:twitter.com" to my query just to be able to find content that I can read without being tracked.
As a whole, I'm not a fan. This strikes me as another move by a social media giant to become "the internet" in the eyes of some people. Maybe that's appealing to the masses, but it's dystopian in my eyes.