noob question to be sure : if we just hodl, we can do this upgrade whenever we want right ?
Yes, you can continue to receive on existing addresses etc, but, your wallet won't update and show your balance (Only DigiByte Blockchain Explorers will). You'll need to update before sending.
If you've got your wallet.dat backed up and in cold storage, say for a decade down the track, then don't worry about it, you're fine, just use the latest when you *do* decide to restore it.