I would absolutely use it! Obvious it's gotta pass the mold and smell test, but this summer I've used some wheat from my mom's Y2K stash. Uh huh, it's at least 14 years old.
The biggest issue I ran into is less gluten content. I'm not sure if it was the wheat or the age, but I was wishing for a tablespoon of gluten in my yeast breads. It worked fine for non-yeast stuff, like pancakes and muffins.