I agree with that, at least, if one considers the protocol. The protocol is what it is, without segwit, and with 1 MB blocks.  That's bitcoin, for now, and most probably for ever.

However, people are free to make software that follows that protocol, or they are free to make other coins, that have new genesis blocks, or that fork off bitcoin's chain.

This whole battle is only about a NAME.  People want a new protocol (one with bigger blocks, one with segwit, one with this, one with that), but they want to keep the name of bitcoin (the brand), and for that reason, they don't want the old chain, the actual bitcoin, to survive: that's the only way to get the name to a new coin as the original bitcoin then doesn't exist any more.

If it weren't for any brand name, people could make as many forks as they like.  In fact, a big error has been that bitcoin doesn't have a version number in its name.  (I'm not talking about the *software*, I'm talking about the protocol).

It is even more amazing that litecoin doesn't fork off, and lets a litecoin with segwit, and a litecoin without segwit, exist.  Because bitcoin being the first mover, its brand is what makes its value ; but for litecoin, I don't see what is the problem to create a LTS (lite coin segwit), which is a bilateral hardfork of LTC at an announced point, and which will exist next to LTC as another alt coin.