There are Brug plants that are 20 years old or more, in Hawaii and also a famous one in Beacon Hill Park in San Francisco that's 30ft. or more tall and has been there for many years.
Here in FL they are subject to nematodes, some fungal diseases, and also the spider mites love them. If you can keep those things at bay, your Daturas and Brugs will live for years and years. They get very large, but don't mind being pruned to any size that suits your growing conditions.
On the nematode problem, the solution is to grow them in large pots, not in the native soil, unless you have a good area you can solarize first to rid the soil of the nematodes. I had one grow for about 3 years in the ground before it petered out. When I pulled it up it was thoroughly infested with root-knot nematodes.
