There's not much more to be said as of yet, as we don't know a time frame, gameplay style, whether there'll be a non-VR option, whether it'll be Steam-exclusive or if PSVR will get it... we don't know much.
What we DO know is that Valve is actually making a new Half-Life game. I can't wait to find out more on Thursday!
Source: https://twitter.com/valvesoftware/status/1196566870360387584

My two hopes. Hopefully it works with my original vive and hopefully it doesn’t make me sick.
I bet it’s a prequel to Half-Life 2.
Prediction: we get a sequel to this game that sets up a third, but that third game never comes. 😂