People have this all backwards. Its not merchants that we need - it's earners. We need to PAY people in BTC. That's how you drive an economy. Give people something valuable, and merchants will flock follow the money. If those with millions of BTC would start paying hoards of programmers in BTC only, they will need spend that income, and that will drive the economy.
If you want to make a river, pour water on the mountain top.
I generally believe the bitcoin economy will unfold as Rick Falkvinge outlined back in 2011 ...
1. Unlawful trade - e.g. Silk road, criminal currency transfers.
2. International trade - wire transfers are too expensive, and credit cards are not accepted uniformly worldwide.
3. Merchant trade, e.g. credit card fees and fraud are too expensive.
4. Investment, e.g. like precious metals but no storage costs and supply is strictly limited.
It is shortsighted in my opinion, to focus on just one of these.
Risto Pietilä, who as a precious metals dealer frequented this forum a month ago, could make a great case for the last category. By the way, Risto I miss your commentary and wish you well.