So this swap is an agreement to sell bitcoin at an agreed rate in the future, right? Does it mean merchants who accepts bitcoin do not need to sell the bitcoin they received on the exchange immediately?
Yes. This is a crucial step towards stabilizing the exchange market and turning Bitcoin into a viable currency instead of an investment currency. Additionally, if these swaps are heavily used, they could create significant upward price pressure for BTC by forcing the market into a longer position and therefore able to price in externalities like deflation, and the demand increase for BTC at higher valuations (wire transfers for large corporations which exchanges cannot currently handle due to the limited market.)
Keep your eye on these swaps, they could serve as a tipping point.
You can get more information here, instead of having that kid posting handicap signs call you an idiot: https://en.wikipedia.org/wiki/Swap_%28finance%29Or a simple explanation here:
http://www.investopedia.com/articles/optioninvestor/07/swaps.asptl;dr: Bitcoin's real value is in the future, not the present. Swaps = Long positions = Long term upward price pressure = Good.
Disclaimer: Please note that I am not necessarily saying that the current $470 price is 'good' by extension, Bitcoin could (still) be overvalued and a market correction could suppress any short term swap benefits.