Perhaps some of the larger merchants will try harder to steer customers to their own CC's. It will probably only work for customers who are HVC's for a particular business, but I can see a contractor dumping tens or hundreds of thousands a year at Home Depot/Lowe's.
A lot of people in the real world probably think that spending $5-$10K in a year at a particular merchant is Big Bucks. To us MSers it's just another day at the office.