Vegan is definitely a growing trend. It doesn't have to come anywhere near supplanting meat-based diets in order to be huge on its own. As with many trends, a person could get rich just paying attention to what's happening in California and is poised to expand to the rest of the country. I can't count how many times this has been true over the 35 years I've lived here.
The reasons are many but health and environmental sustainability lead the pack along w animal cruelty issues. I have not gone vegan but have many close friends who have and I eat a lot of delicious vegan meals. I avoid anything processed and try to eat only organically raised meat and fish. It's easier to do in a big city than somewhere rural unless you're raising your own food animals organic or have a source. The commercial beef and poultry industry is bad news.