Though whether or not any of them will be released is anybody's guess.
Half-Life 2

In a recent interview conducted by Famitsu (via Tweaktown) with long-time Valve employee Greg Coomer, the Half-Life studio is still very much in the business of creating games. Coomer told the publication that Valve has a lot of projects currently in development.

Coomer says, "Valve has a lot of games in development. We will continue to release games. Game development is very important to Valve. I don't know the exact numbers, but the percentage of employees involved in game development is high. A lot of people are involved."

This would not be the first time that Valve has had several projects in "active" development. However, the number of times those games have actually been completed and released is quite miniscule.

The big question though is if Valve is working on more entries in the Half-Life franchise. Half-Life: Alyx was absolutely incredible, but will there be any more in the saga of Gordon Freeman, be it VR or otherwise? Coomer simply says that Valve wants "to continue exploring the Half-Life universe."

"Half-Life: Alyx was a really fun game to make. Even for (those of) us who worked on that world, it's still fun to go back there and tell more stories.

"Also, there are many challenges in virtual reality, and it was an interesting task to solve them. Half-Life works are always accompanied by technological innovation, so it was a big step in that sense as well... Half-Life: Alyx is a sign that Valve has more to say about that world.​"
Coomer also noted that he would "like to make another Portal someday." A new Half-Life and a new Portal game? Be still my beating heart! Of course, with how many times we've heard that Valve is "working on" this or that they're still dedicated to continuing the Half-Life franchise, this is very much a case of "I'll believe it when I see it."