Sorry to be a nay sayer, but it won't work. If this requirement were set in place, a patent troll will get around it by hiring a coder for a week to get something out really quick that does something nobody needs and then they'll sell one copy to their grandma. This won't evoke any real change unless you manage to make it very complicated. There would have to be mandates in the law like x% of your company's revenue must be from actual sales of the product or something like it.

The better solution is to just end software patents. They have no value in the current software economy.