Bitcoin requires a hard-fork to address at least some of its inherent technical limitations. This is a huge risk and one which could easily undermine the perceived value of the entire "currency".
Also, you say merchants will start accepting 0 confirmation - this is unlikely - at least in the near/medium term. In reality, Bitcoin has very little utility in the world that is not better satisfied by Visa/Mastercard, however its largest undoing - and something Bitcoin alone cannot address - is the volatility. And this is where BitSharesX BitUSD is a winner.
Getting greater recognition for this is unique feature not only requires a nicer desktop client, but also a web-wallet like blockchain.info for greater mass market penetration. But most of all, merchant adoption is required, and that means convincing BitPay or Coinbase to back BitSharesX for seamless merchant integration.