I basically want to have my Bitcoin seed (from the old ledger nano) on my Nano S and for all the alt coins wallet.
1 Ledger Nano S - (Nano Seed) Bitcoin - Ether - Vert - Litecoin
2 Ledger Nano S - (Nano Seed) Bitcoin - Ether - Pivx - Viacoin
Would work, right?
I can't confirm since I never had a hardware wallet.
But why don't you try out? Import your old seed in your new Ledger Nano S, write out the Ether or other altcoin address, recover it again in the same or second device and see if both wallets are the same. Maybe even send a minimum amount to see if everything is ok before risking a big amount of cash.