Kleenex and Xerox were both (somewhat) recently in danger of loosing theirs. They both pulled pretty big campaigns to un-verb their trademarks. Google still has a bunch of other products that people are familiar with, so they are in less danger of loosing theirs right now, but give it some time (like 50 years, not 10) and it may happen, especially if they get broken up for being a monopoly. (Which has been mentioned)