If he patents blockchain, would it mean that it will not be open source, and does it mean all other altcoins may also be affected?
He can't obtain a valid patent on that because bitcoin is open and unpatented years before Wright ever heard of it. Once something is published that becomes a bar to patentability called prior art. But this doesn't stop someone from making spurious patent lawsuits as a form of harassment, they'll ultimately lose, but they still waste their opponents time and money.
Of course, he could attack altcoins but most major altcoins have massive premines that they can use to pay him off-- or use to fund litigation to stop him. His scheme mostly centers around harassing Bitcoin and Bitcoin forks and so far he's left other altcoins alone.
This is going to be used for fud to every altcoin which they can constantly attack. All they need is media and still can manipulate the market thru it including BTC. Looks like the government will be on his side too.
What amuses me is that Craig Wright is an awful coder which should have automatically shown that he wasn't Satoshi Nakamoto. Only a genius (like Hal Finney) could have written the whitepaper and made the original code. Craig Wright is some loser with a collegiate level understanding of coding.
His coding capability I guess wasn't the point of it, It was sort of his idea and partnership for creating BTC which was said by Kurt Wuckert recently who is an advocate of the BSV. CSW did have some alliance even when he is obviously can't code well.