After the initial release of the game, maybe the developers can release little optionally downloadable packs of content for the game, and not actually working on them during initial development. I have some ideas for some myself. REMEMBER: I am not demanding that the devs do this, but it is a SUGGESTION.
Sharpshooter pack
For people who liked the HD weapons for the original Half-Life. It replaces all of the current weapons with the ones in the original HD pack except for the weapons that remain unchanged except for higher poly (if it’s hard to understand, it means like replace the Glock with the Beretta, the SPAS-12 sawed-off with SPAS-12 with the stock folded, the MP5 with the M4, etc.)
Filmmaker kit
access to the TF2 replay editor, for the people making a Half-Life/ Black Mesa movie. I, for one, am one of those people. It should also add a 3rd person view of Gordon with many realistic 3rd person animations.
*Smart Moving Pack
should add a whole bunch of first person animations, picking up items similar to in L4D, scripted animations, all inspired by this video: https://www.youtube.com/watch?v=wtIp8jOo8_o&feature=player_embedded