Blockchain Luxembourg S.A. & Blockchain (US), Inc. seems to be holding the Blockchain.info and Blockchain.com domain from much time now and there name sure sounds like the best emerging tech word on the Planet. The company is providing some of the mostly used wallet services for good sort of time with no issue and hs succeeded in creating a type of monopoly in the field under the most interesting  name "BLOCKCHAIN"

But just claiming a similar name which is owned by other entity makes no sense as they can just buy it by offering a good price to the current owner if they want to protect there branding this much. I think even if the owner of the "blockchain.io" domain refused to sell it to Blockchain Luxembourg S.A. & Blockchain (US), Inc. it should not be much of the problem to them as they are already a giant in the crypto wallet business and anyone using their name for offering services would just be pointed as fake and can be eliminated by the company itself in a very easy way.