Yeah, and that's called a fork. The chain doesn't vanish; a new chain is created, forking off of the old one. That's why we have both Ethereum and Ethereum Classic.
Oh wait, you're talking about a 51% attack. Read the whole article that you linked. It is amazingly difficult to perform, and as the number of nodes goes up, it becomes even more difficult.
Has anyone successfully performed a 51% Attack on Bitcoin?
Nope, not yet.
Some miners have come close to reaching 50% or more of the total mining power over Bitcoin’s history, but nobody has actually performed a successful 51% Attack.
If Big Daddy Bitcoin hasn't suffered a 51% attack, I find the risk of that happening vanishingly low.
There have been three. BTG, ETC and VTC. All three of those are Proof of Work. PoW is going by the wayside, I'm hopeful that Proton would be using Proof of Stake, which is a much more difficult model to 51% against. (You would need to possess 51% of the tokens.) Even if someone managed to do it, it would still be noticed pretty much immediately, and then you'd fork to a new chain and move on.