What web wallet are you talking about? I would recommend you move your funds to a software wallet like Bitcoin Core or Electrum. You may also want to consider using a paper wallet or a hardware wallet if you plan on holding your funds for that long.

I personally wouldn't be concerned of any upgrade rendering your coins inaccessible. This can only happen in a case of massive unprecedented cryptography breakthrough (quantum computing breaking through private-public keys combination, etc.) and nothing of the sort is going to happen within the next 7 years. This is also very much a doomsday scenario -- I don't think Bitcoin will survive if things get bad enough that old coins get locked out because of protocol changes.