I wished they hire the Arkane team that got laid off. Put them to work on a new single player ip and let Victor Antonov add some of his design into it.
They dont have to do anything new, just make it good enough, like Titanfall 2.
> I believe they also said they don't want to do more of the same
I've heard this too, with Half Life they want each game to be groundbreaking. Arkane have done great games, but they're not all groundbreaking, and arguably none of them are to the level that HL1/2 were.
That's why they should hire someone else to do the leg work (That's what they used to do anyway). There isn't exactly a lot of unique things in Portal 2 compared to the original but the sheer polish and testing Valve applied to their games (when they want to) is still unmatched.
Portal 2 added co-op as the big gameplay change vs. 1.
But Gabe has said Half-Life specifically is what they consider their ground breaking series now. So there won't be a 3 until they can push a boundary again like the first 2 did.
From all the leaks, it sounds like the big change for HL3 is currently advanced materials – destruction, traction, behaviour, conductivity, etc. This would make sense as it plays into the material work in Portal 2 and the deformation work in HL2:EP2-3, as well as the physics puzzles in HL3. Additionally it sounds like gravity may be a core feature of the game.
This is all speculation based on code leaks, and it's possible this is all true and they still don't release anything because the project stalls. Supposedly the game has moved into the later stages of development, but I'm not fully convinced by that part of the leaks.
They dont have to do anything new, just make it good enough, like Titanfall 2.