It is possible they have successfully settled out of court because the fee is much less than the cost to litigate, and an IP lawyer might suggest that. A case could go on for multiple years, but it could also just get thrown out if you are able to easily prove prior art from before 2002 when the patent was initially filed. It's always worth talking to an IP lawyer though. It isn't expensive to talk for a couple of hours.
@jermaustin1 is right. Nuisance lawsuits rarely go to trial because the cost to litigate is far higher than the settlement demand. Patent assertion entities are usually looking for a quick payout and these cases typically do not last long. Many patent litigators will give you a free one-hour consultation. It does not hurt to ask. (Source: I am a patent litigator, and my firm does free one-hour consultations. I've even done longer ones for free. When you talk to the lawyer, just say that other firms are waiving the cost to discuss your initial options. That is not unusual at all.)
I retained an IP lawyer for a copyright troll a few years back over an image that we used on a blog that was credited properly when we used it, but the copyright troll bought the image, and was demanding about $12000 for the license. IP lawyer was only around $500 for retainer, and he made the troll disappear (not sure how, but also do not care).
Sometimes just the threat that you will actually go to court over something will make a troll back off.
