1. A offers to sell laptop for 2000 coins, and escrows 2500 coins as security.
2. B offers to buy and escrows 2500 coins as security.
3. B pays 2000 coins to A.
4. If A refuses to send the laptop, both A and B have lost 2500 coins. Therefore, A has an
incentive to send the laptop, and B can't use this system to put A out of business.
5. A sends the laptop to B.
6. If B refuses to acknowledge receipt of the laptop, both A and B have lost 2500 coins.
Therefore, B has an incentive to acknowledge receipt of the laptop.
2. B offers to buy and escrows 2500 coins as security.
3. B pays 2000 coins to A.
4. If A refuses to send the laptop, both A and B have lost 2500 coins. Therefore, A has an
incentive to send the laptop, and B can't use this system to put A out of business.
5. A sends the laptop to B.
6. If B refuses to acknowledge receipt of the laptop, both A and B have lost 2500 coins.
Therefore, B has an incentive to acknowledge receipt of the laptop.
It'd work, but it'd be tough to fit into commerce. You'd require businesses to have as much cash on hand as products shipped in a given day. Many small businesses don't have that cash cushion.
Even individuals could feel the pinch -- I'm not sure I'd want to convert $2000 USD to BTC to buy a $1000 computer ($1k used for escrow).
My personal opinion would be to keep any notion of trust away from bitcoin. It's cash. It can be spent, stolen, lost, defrauded, etc. The world has volumes of law to deal with issues of trust, fraud, and theft. If you don't trust someone to send what you buy, you probably shouldn't be doing business with them.