This means RBF provides no guarantees, it means that in BTC you must wait for confirmation(s) - as you restated. So BTC cannot be used as P2P digital cash, as it was intended.
If that makes you panic you should probably ask yourself why.
They've never did provide any guarantee.
About the digital cash part, I think that's debatable. The fact that people are used to transfer cash instantly, doesn't mean that any kind of cash have to do this. Bitcoin, by design, makes you wait for confirmations. Even if this "flaw" (as you seem to see it) would not exist, even then you would not be able to pay with Bitcoin at the grocery store (just imagine how big the queue would get!)
You can still pay with Bitcoin, however, for your plane ticket, for your vacation, for whatever you are shopping online. It still fits to the P2P digital cash use case and one can properly wait for the proper number of confirmations. And for the grocery store, .. we need something added to Bitcoin. Maybe LN, maybe something else.
And I'm not panicked at all, nice try to twist my words. Only newbies with insufficient knowledge can get panicked by all this ... story.