I very much like the idea of stablecoin. This would be a version of bitcoin that's better suited for commerce than the original. In order to use a currency in commerce, stability is very important. No merchant wants to constantly have to change prices.
As of today, you are wrong: many bitcoin merchants still change prices very often, even though this hurts stability. When they start to grow up and offer their services for dependable prices (I would call it that way at the point where they don't change BTC prices more often than e.g. USD prices), there will soon be no market for bitcoin adaptions with an additional single point of failure added, like stablecoin or goldcoin are.
I would not see them as an alternative to bitcoin, and neither would most of the people I work with, as these approaches backdoor the dependability which bitcoin achieves through decentralization.