I love the discussion on how to get people using bitcoin. I think the incentives need to be strong enoug. 

The merchant needs to give at least 10% off to incentives people using bitcoin. 

The merchant saves 3% on credit card
He accumulates a currency that is deflationary
But the big one, he can easily not declare his bitcoin revenues (like cash) and save around 20% on income tax. He needs to be brave enough for sure for that. 

Also you can't say the last point out loud. He needs to figure it out by himself. I try to tell merchants it's like cash, it's not tracable so they connect the dots.