Do you really think some lawyer can get thousands of independent businesses and hundreds of thousands of individuals to abandon their usage of this word? No chance.

What's the alternative? An expensive community-run foundation to hold the trademark around the world, together with the cost and effort that it will consume? And all the infighting deciding who controls the foundation, and who can use the foundation-held trademark, and how they can use it? Maybe if Satoshi were around to hold the trademark it would work, but not otherwise.

It's not worth it. Just ignore this douchebag unless you get a C&D. In the extremely unlikely event that you do get a C&D, don't pay to settle, and don't pay to defend. Just temporarily switch to the separate un-trademarked words "Bit Coin" until the douchebag gives up wasting his money. And make the most of the free publicity that your business will get as a result of publicising the C&D!