Apparently there's an expansion pack due in the summer. As far as i know nothing really offical had been released about it. But i read a newspaper article saying that you didn't play Aleyx Vance.
I'm hoping Colonel Shepard makes an appearance, afterall Gman took him too (if you ever played Opposing Force you'll know who i mean)
If you didn't then basically Colonel Shepard was a marine sent in to Black Mesa to take care of the scientists, especially Freeman. So things go a bit wrong and the government send in the Delta team or whatever they are to take care of the marines. So you are basicaly trying to escape with your life, and you catch glimpes of Gordan every now and again, the coolest one is where you see him jump through the portal into Xen. And then you go on to kill the really big monster from Xen while gordan is killing the leader of Xen. Gman then turns up and does effectively what he did to Gordan.
So i presuming Colonel Shepard is around and able to turn up in City 17. I think it would be pretty sweet if he turned up during the time Gordan and Aleyx are stuck in the slow teleport out of Nova Prospect. You could have him leading the rebellion that occurs just before Follow Freeman. You'd get to shoot lots of striders anyway
Anyone have any idea what the story line might actually be?
) Shepard to make a comeback...why else did the G-man put him in suspension? 
Having said that, there's mentioning of Shepard fighting in the 7-hour war iirc. In one of the newspaper articles on the wall somewhere. Meh.