Hardforks “can” result in a ETH/ETC like split, but that does not have to be the case. For example many other coins had hardforks in the past without splitting (Dogecoin, Namecoin, Monero has regular hardforks)
Also BU does not give miners complete control over blocksize, to override the blocksize they have to create 12 blocks in a row that are oversized (the default for AD is 12, but it is a config option, can be set higher), which is very risky and expensive if the network does not agree, because if this chain is not long enough those blocks will be orphans, no block reward then. Also if miners collude to do this it would mean we have much bigger problems, then we should switch PoW asap (keccak).
Bitcoin is a voluntary system, i think it is very unfair to call the miners not installing segwit “blocking”, they are just not opting in.
Maybe you had good intentions writing this, but I think you have been mislead somewhat. But I agree with some of it, people should inform themselves and draw own conclusions.
Not sure if I can add links here, lets try. Here: http://archive.is/z9nt1 is a great write up from a “legendary” bitcointalk member, about why it is absolutely necessary for the blocksize to increase, even with payment channels segwit and so on, it will still be needed.