If just 20% of prospective buyers devoted 1/2 their budgets to a common open solution, they could break out. If there were a tiny company offering an old school model with modern features at a competitive price, that would be enough. Then, if farmers choose to lock themselves in, it would be a real choice and their own fault.
BSD didn't need legislation. GNU didn't. Windows still thrives, but people have a choice. Just convince ADM and a few others to throw some pennies at a startup. Except that the new licensing greatly benefits those giants. So you'd have to convince 100s of little guys to throw big money your way.