All kinds of patents expire after 17 years.
But if I'm not mistaken they can get indefinite patents as well which seems more like abuse than privilege.
17 years as well...seems like to long a time frame to me., but again I'm not expert. I'd have gone 10 years max.
But it seems from my readings that applying a reasonable expiry date to them would solve so many issues.
So say an assumption would apply that after say 5-10 years a technology would be common place and hence no longer unique, and that a company that couldn't capitalise after that period shouldn't be able to be in a position to hold up an economy.