If it's online and has never been online, at least you can be sure it can't be hacked.
I think that you meant "if it's NOT online and has never been"...
how can I be sure that in 20 years from now, Exodus wallet will still be a working product, that I can download from a new computer perhaps and import my seed into? This never made sense to me, I'm depending on the creator of the software it seems to me.
You don't have to rely onto a working product. You have to rely on existing standards.
If you generate a BIP39 seed, that should work also in 20 years. If you save a private key, that should also work in 20 years.
I agree with LoyceV. For long term holding I recommend you generate the wallet in a safe offline environment with no persistence/storage. Write down (onto paper) the seed or private key, write down the address (or, if it's HD wallet then any address), verify thoroughly what you've written down (maybe use a wallet to recover from seed or private key and see if the address obtained is the same), send your coins there, watch your wallet on online block explorer or import the address as watch wallet. As long as your private key or seed never touches anything online, it should be safe/safer.