My mother died 30 years ago this coming Dec. 13th. For me, the holidays will forever be tied to that event. I was in tears today because they were playing O Holy Night on the radio while I was on my way to work: one of our traditions was watching the Perry Como specials together, and it just wasn't Christmas until we heard him sing that song.
So, yes, they will never get over this. Their lives will go on...are going on...and there are things you can do to help.
Offer to pick up out-of-town relatives from the airport. If you have a spare bedroom or a sofa-bed, offer to let a set of relatives stay with you. Offer to go over and shine their shoes before the funeral. Tell them you'd like to offer to write the thank-you's for condolence gifts...so they only have to sign them. Offer to pay a young adult to stay at their house while they are at the funeral and/or funeral home (where I came from, it was pretty common to hear about houses being burglarized due to funeral times being posted in the newspaper).
Most of all, remember that THEY didn't die. The worst thing you can do is stay away...unless they say that's what they want. They need contact with the people who are part of their every day lives now more than ever!