Defending weak patents thru litigation is expensive when they put up a fight and sue you right back.
Look at the example of Apple I. Only game in town, Apple makes millions and stay’s proprietary. IBM comes out with PC and open architecture, the world is quickly swamped with PC clones and Intel gets 90% of the market.
Apple is running the replay with Iphone vs Android.
Apple will try to hold out as long as it can. I remember during the PDA days, people were still buying black and white Palm Pilots even though ipaqs were more powerful. Of course, eventually Palm was completely wiped out.