I agree with you on some points that all miners should adopt and vote for the activation of segwit and will not bring another issue of activating hardfork. If all miners will agree then we will have a fast confirmation of transactions as well as the increasing value of bitcoin. But I will also disagree with one thing, its about the bitcoin split. When bitcoin will split it will not go bankrupt, the value maybe deflate since users will be divided in two groups. But even if bitcoins value will drop due to bitcoin split but it will still recover like in the case of Ethereum and Ethereum Classic.
This is what I expect a reasonable miner should do and I believe this matter has been put to rest with the several news across the forum about the acclaimed August 1 activation which I believe is moving towards this direction, but if the miners are now adamant and want to kill this initiative then its a lose all for everybody because nobody would be willing to pay high transaction fees in the face of falling prices.