It will stay good for as long as the seal remains intact. You can shake the tin and it it sound like grains of rice in there it's probably dried out. Even then it can be re-hydrated to smoke.

Virginia tobaccos, like the McClellands mentioned above, age very well, becoming smoother and richer as the sugar in the tobacco ages.

Just keep the tins from rusting and you should be OK. Newer tines are an aluminum alloy and don't have this problem.

BUlk tobaccos can sealed in a Foodsaver vacuum bag.

My problem lies in reconciling my gross habits with my net income.
- Errol Flynn