If Bitcoin rejects segwit it will be because of political reasons, philosophical feelings or in some cases people actually believe you can have an unlimited blocksize on a decentralized network. The code has been vetted, tested and is well written. Not sure why anyone would suggest otherwise. If you reject segwit fine; but, dismissing the code seems somewhat disingenuous. It's good code.

That said it remains unknown what will happen to bitcoin. If two chains emerge value might split down the middle or some variation of percentages. The summed value might be far less than the current total. Definitely, some value might transfer to other coins. We will find out soon enough.