I wouldn't think they could ever win anything. One of the rules with patents is you can't just kick back and wait for your competitor's product to grow and sue 10 years later.
Considering WiFi is almost 20 years old, and has practically surpassed 'ubiquity', I'd say that ship sailed.
That's the beauty of the scheme. They don't HAVE to win anything. They threaten to sue for $2,000 to $5,000 which is less than the cost of hiring a lawyer to defend. 98% of the people threatened pay up. Some miniscule percentage are incredibly cussed individuals who are willing to spend thousands of dollars just to be right... maybe they'll lose those cases. It doesn't matter: they're still making huge amounts of money.
The only threat to the scheme is having your lawyers be sanctioned for unprofessional conduct. If there was NOTHING behind the threat, this would be a real possibility (like, say, if you tried this scheme when you didn't even HAVE a patent). But as long as it's a plausible case, the threat works and it's highly profitable.
Never heard of that rule. Perhaps you are confusing with trademarks, which you must defend?
Or you are confused about the damages - you can't collect damages on anything that happened before you told the victim "you are infringing, now stop or pay me $XXX". But you definitely can collect from that point on (triple damages, if willful infringement is established)
IIRC, you could argue in court that the patent-holder knew that infringement was happening, yet only decided to come out of the woodwork in the 11th hour. I think that this defense has worked in the past, but you would need to spend a bunch of money to get to that point though.
Considering WiFi is almost 20 years old, and has practically surpassed 'ubiquity', I'd say that ship sailed.