I think they should just stick to the can, right up to around the litre mark. I know that Monster do litre cans with the screw top cap over on your side of the water - and it works really well. (What's that on your money? 30 ounces or so?)
With paper, you're just asking for damages and exploding cartons. I can't see how it can possibly work. Then again, I never thought COVID would turn into a global pandemic. So...
(I'm reluctant to trust my foresight nowadays.)
Whatever happens, I think we can all agree that the world will be a better place without plastic bottles. They do nothing to improve the taste and they're actually nasty to drink out of. I don't know why the supermarkets stock them, surely flavouring drops and refillable Co2 canisters will give you gallons of the stuff for a fraction of the space.
Or am I just being stupid?