Trolls usually don't file patents. They usually acquire them, usually from a company close to going bankrupt. Then they sue other "medium-size" company in a jurisdiction with a friendly and corrupt judge.
Even if we stopped issuing new patents today, trolls have enough fodder to survive for the next 100 years.
I thought patents expired 20 years from the file date? So you could only troll for ~20 years + anything manufactured using an infringing process. (so "you owe me royalties on the widget you made 10 years ago" is valid.)
Even if we stopped issuing new patents today, trolls have enough fodder to survive for the next 100 years.