- If you make a new wallet, (seed), and move all your tokens to it, will the other (old) wallet disappear?
- Will the old wallet (seed) clog the tangle?
Is there a preferred way?
Is there ever a time/situation where we will HAVE to generate a new seed. (Except because of improper address reuse prior to a snapshot -- for recovery purposes).
- In other words can our seeds remain permanent if we follow the present best practices?
No you don't ever need a new seed when you follow the present best practices.
The only reason to need a new seed is if you lose your old one or if your seed gets compromised—as in someone else knows it.
The seed does not get compromised through address reuse. Only the private keys can get compromised. They are derived from the seed. More in this answer. Regarding the first few points, the seed is never in the tangle. Thus, it can neither disappear or clog the tangle.