http://www.washingtonpost.com/blogs/the-switch/wp/2013/10/01/valve-has-registered-a-european-trademark-for-half-life-3/

Quote :

The last time a feature-length Half-Life game came out, John Kerry had just lost a bid for the White House. We were mired in two wars we didn't know how to end. NASA's newest Mars rover was a little guy called Opportunity.
Fans have been waiting almost a decade for another adventure with franchise protagonist Gordon Freeman.
Here's a sign — albeit a small one — that the drought may soon be over: Valve has filed for a European trademark on Half-Life 3. That's it in the screencap above. For more, run a search on the European Union's database.
There have been false starts before, of course. As far back as 1999, Valve snapped up the domain half-life3.com. It's been dormant ever since, redirecting people to a promotional page for the Orange Box, which itself debuted in 2007. But at the very least, this latest development gives fans a little more cause for hope.

HL3 won't happen.

It official, Valve trademarked/copywritten it.

More news:
http://www.computerandvideogames.com/431918/half-life-3-development-team-revealed-via-network-leak/