De-Ep1 weapon resprites aren't planned for anytime soon. The only thing I have set up for Winter Break is finishing the Hierophant and the Hellstaff replacement sprites, and the Hellstorm secret level. Also fixing old map bugs and texture offset problems has been the primary goal of late. I want to polish up the first 2 episodes as much as possible without changing the quality and get cracking on Episode 3. Sometime during the the development of Episode 3's monsters, I will finish the Episode 1 weapons respriting.
If you wanted to make marine skins for the DE weapons, the new design will look similar enough to the old one that you can pass with just putting the old weapons onto the marine. Infact, they will have the same pickup sprites, with the exception of the 3 shotguns. I'm mostly just fixing the artistic mistakes on the weapons, such as shading and coloring that seems to look jacked up when I really start looking at it. However, if you want, I can actually finish the pick up sprites for the weapons first, so you have something to put onto your marine things (since I already know what their designs are gonna look like - mostly figuring out how to animate them correctly).