Norman Walker (author of
Become Younger and many other pro-raw books) died peacefully in his sleep. He was 99 and was healthy and active until he died. He was a big proponent of consuming fresh veggie juices every day. He was raw for decades but not 100% vegan since he included small amounts of raw dairy (mainly goat's milk if I recall), but he admits in his books that any milk products are mucus-forming and certainly not needed.
Assuming you don't succumb to other lifestyle diseases or commit suicide, you're probably most likely to die from an accident.
You can also screw up the raw diet and make your health worse if you don't know what you're doing, but there are so many great resources available now that this isn't as likely if you're moderately intelligent.
The quality of produce is a big factor too. I'm doing mostly organic right now, with some foods from my own garden. I have a nice crop of tomatoes coming in now. Ideally I'd love to plant an even bigger garden and grow more of my own food, even if I just grow some things in pots.