A copy of wallet.dat contains all information you need to spend or transfer your coins at any later date (except the scenario described by teukon).

I would however advise against long term storage using wallet.dat for practical reasons:

Chances are rather good that in a few years
a) a current Bitcoin Core will not even have a wallet, therefore unable to import wallet.dat
b) your old Bitcoin Core might not be able to join the network, e.g. because current nodes use a different chain download protocol and you can't find old nodes.
c) your old Bitcoin Core might create transactions that are no longer forwarded/accepted by the network because they violate some later introduced soft-fork rule
d) your choice of new wallet might not be able to import wallet.dat

There are developments in Core that support assumptions a-c and d is probable because all modern wallets use HD key generation instead of a random key chain, that is wallet.dat.

I suggest you move your coins to a more modern wallet, e.g. the TREZOR and store its recovery seed in your long term store. Also assume that you may need to move on again later.

It is a bit like converting your videos to a newer codec. Ignore the development and will become a pain, but will work with sufficient expertise.