That would be really absurd to see digital currencies in paper form. People will not be able to accept this entirely opposing idea to the real objective of bitcoin or digital currencies. World is already having enough of fiat and a lot of variety is there. People were and are attracted to bitcoin because of its digital nature. I don’t think it is great idea to attract investors
If you mean paper as in real paper, then it is one thing
But if you actually mean just physical representation, i.e. not necessarily in paper, it is a completely different story. As I mentioned above, there are physical devices (technically USB sticks) which can be used to transfer the ownership of private keys without anything being recorded on the blockchain, ever
If you ask me, for all practical intents and purposes, this is what physical bitcoins would be. And while their area of application may in fact be limited, they still have some use. Say, if you want to receive bitcoins from or give them to your counterparty in a truly anonymous way, this appears to be only the reliable way to go (and no, mixers don't cut it)