I do not know of any other blockchain, but can not happen to bitcoin blockchain which is getting stronger all the time than before.
Dude, everything can happen as long you have enough power source on the network to do that.
If you don't know about the 51% attack, try to read first and your question is bitcoin can get a 51% attack? the answer was yes but you need to have a lot resource to dot that because is not easy to dominate the network with more than 51%.
I get your point which only proves the theory not reality, but my point is, it is not possible with the level of hashrate generated by bitcoin miners for bitcoin blockchain to suffer 51% attack. With such hashrate, it is not possible. If the so called ethereum, litecoin blockchain and some others that have far lesser hashrate do not suffer 51% attack, not to talk of bitcoin with the greatest harhrate. Another thing is the level of confirmation, even very possible a coin with 1, 2 or 3 confirmation to suffer the attack, while the 6 confirmation coins won't, which means 51% attack also depends on the depth of confirmation. But as of history and recent, bitcoin as never suffered 51% attack because
it can practically not happen, only theoretically.
yeah, can happen in theory, but cannot happen in reality, due to various constraints, one being that you can acquire all that equipment in time, to reach 51% malicious hash-rate
only thing that could happen, in case that China launch their own cryptocurrency, their miners could take down BTC network, since more than 50% hash power is there, but I do not think that is really realistic view, BTC is here to stay, as most other cryptocurrencies, while Ethereum Classic will probably cover just a niche, their founders give up on it, and community is not that strong to improve it in long-term