I think it is a new asset in that as it is being established as a SoV at the same time as it's capabilities of a MoE are being bootstrapped. I think most money has had to really become the first one before it could be the second, and I think Bitcoin is going to overlap more than that.
I see it slightly differently: that it's true calling, as it were, is as a personal, portable, permanent SoV. A kind of undying meta-wallet that we can trivially take across borders and generations. We can choose to grow our stash all our lives, give it to the state in taxes, pass it on, spend it, whatever - it is completely within our - the keyholder's - control. Not the border guards. Unbeholden to or trusting any third party, bank or societal construct. It becomes purely that part of us needed to exchange, from time to time, strategic value with others. In that sense, no other currency is needed.
But the means of exchange on an everyday basis, the buying a coffee, is a red herring. It has some importance, yes, but only to demonstrate atht the transfer of value can indeed be performed, trivially, securely and irreversibly. It's a kind of proof of concept to the doubters.
Undeniably, for banal shopping a credit card works better. Sometimes you don't trust the person you're buying from. In that case you're buying a judge for that credit card 3% who will usually side with you. I don't have a problem with that. In fact it seems perverse that fighting that service is the ditch Roger and Craig are happy to die in. Let 'em.