The short answers is no its not too late for the wisdom tooth extractions, and yes braces will work on an adult.
As for wisdom tooth extraction, at 21 you're at the upper end of the ideal age range for extraction (16-21). At this age, it's still likely that you haven't had the complete formation of the roots and the subsequent "condensation" of the bone around the roots. With the bone not as "dense" as it can be, this will generally lead to a little easier extraction of the teeth (read this last line as less potential for post extraction discomfort). As for the nees for extraction, the guidelines that I use in my office for my patients are as follows: 1) Are the wisdom teeth fully errupted (through the gum) 2) Are the wisdom teeth decay free, or atleast of similar decay status as the adjacent molars and 3) is the health of the gums around the wisdom teeth no worse than that of the adjacent molars. Three yes answers and they're candidates to remain in the mouth. One or more "no's" and I reccomend that they be extracted.
As for adult orthodontics(braces). The fastest growing groups of patients receiving orthodontic care is adults. In fact, my wife who is an orthodontist has patients in their 70's
I myself have patients in orthodontic treatment in their single digits, teens, 20's, 30's, 40's and 50's. So whenever you're ready for braces, the orthodontists will be ready too!
