Odds of Hanging On
The Bureau of Labor Statistics projects a higher than average growth rate for the glazier trade over the next several years (source). We'd call that good news for staying in the biz. Additionally, with construction in urban centers climbing as more people move to cities, there's lots of work from which to choose.
New skyscrapers, glass-and-steel condominiums, and the basic wear-and-tear of street-level windows ensures that the glazier business is sure to stick around. If it's the right fit for you, maybe you'll consider hanging on as well.