Is WiFi failure something that happens? I've never seen one. I did upgrade a few cards (in one to go from B to G, in other from N to AC), and I replaced a few broadcom cards with intel ones to get better Linux support, but I don't think I ever saw a broken card.
I think the theory is that cards go out of spec and start connecting less reliably. I replaced a friend’s WiFi card the other day when they were about to throw the laptop out because connectivity was poor (Windows, and it wasn’t a driver issue). Obviously you also need a reliable access-point (that’s a much more difficult topic to address!). And don’t forget some secondary means to connect to laptop to the internet or you can’t download the driver!
