Here's what's happened at the company I used to work at and what happens at many other companies:
1) IBM comes and says hey you're violating these 10 patents. Pay up.
2) Targeted company goes, hey we're not. Company spends X amount of money and tons of time to prove that they're not violating the patents.
3) IBM goes, oh ok, yeah you're right. So you're not violating those 10 patents. Well, here's another 10 we think you're violating. Now...we can do this forever or you can just pay us $1M/year and have us go away.
4) Targeted company does cost-benefit analysis of legal fees to continue to fight IBM indefinitely or they can pay this "license" fee. Company decides pays $1M to "license" IBM patents
oh and postscript, Targeted company wises up and decides to build up its own IP portfolio as a defensive measure and fills the patent system with even more useless patents.