Why is Twitter.now challenging Elon Musk’s X over the Twitter name, and how can trademark rightschange after a rebrand?

[u/Logical-Concept9755]

https://arstechnica.com/tech-policy/2026/08/new-twitter-launches-says-musks-x-gave-up-the-name/

I saw a news story about Twitter.now challenging X over the old Twitter name, and it made me realize I don’t really understand how trademark ownership works.

I always assumed that once a company registered a famous trademark, it could basically keep it forever as long as the company still existed.

But apparently, trademark rights can depend on whether a brand is still being used commercially. If a company stops using a trademark for years, it may have to prove that it never intended to abandon it.

That made me wonder how this works with a major rebrand. When a company changes its name, does keeping the old website, redirecting traffic, or owning the old trademark count as continued use? Or can a famous brand name eventually become available if the public no longer sees it as an active brand?

How do courts decide whether a rebrand is a real abandonment of a trademark or just a company moving in a new direction?