Suppose someone wants to do long term cold storage. I am talking about 5-10 years.
Suppose in 10 years Electrum no longer exists because all the nodes are down or the current version 2.8.x just becomes obsolete.
Is there anyway to save a copy of the wallet with the seed and be able to see the private key, and then later sweep that address to another address?
It is not feasible to do cold storage for such a long time using
any software. Bitcoin could change completely in 5-10 years.
Manually storing addresses using paper wallets would probably be a more ideal method for such a long term cold wallet. You could also easily export the private keys if you are using Electrum for a cold wallet. It just gets more time consuming if you use a large number of addresses unless you use a tool like previously mentioned to regenerate the addresses.
Yes in theory it's possible to do a lot of things. As long as you have the private key then anything is possible. An electrum wallet is a private key in another format i.e. a seed that leads to a whole tree of key pairs. So if you are willing to do the work when the time comes to spend your coins then anything is possible. There
will be work involved because in 10 years a lot could have changed.
Probably in 10 years time we will all have migrated to using lightning. I doubt there will be wallet software that will support spending directly on-chain like we have now.