Valve is to Game Design what Mercedes is to Car Design.
I don't think what people want most is the Half-Life story. They want to see Valve pull out an amazing gameplay experience that introduces new ideas and concepts and accelerates linear shooter design and narrative telling far ahead. That's what both Half-Life games were about. HL1 especially was amazing because it put the narrative story behind you and put the player story at the forefront. HL2 was a technical achievement, although I personally feel it went a tad backwards in narrative-telling.
With Valve stubbornly refusing to do anything aside from small DLC, hardware and store-management, it's a bit of worry as to if Valve still has it in them to make an amazing game, or if they'll be a bit rusty when they dive back into it.