I started replying to @Pipefish where his post appears, but realised my response is way off-topic for that thread, so here’s a new one…
The big question being, whether that is something that can be done with the 1970s back-end. I suspect (a rough guess as a complete outsider), that the big/old banks can probably get 85%-90% of the Monzo experience with a well-designed app. But I imagine the last 10%-15% will be impossible if they don’t completely rebuild their backend infrastructure. And this is before you consider the features Monzo will be able to build in the future due to the flexibility of the infrastructure they’re building, and the marketplace which will be key to a whole new way of managing your finances.
All this is also to say nothing of the internal tools Monzo has developed to allow the level of personalised 24/7 customer support we’ve come to expect
As I say, I think the big banks probably can get mostly there by throwing money at the problem. But fully closing the gap is a much larger problem for them, and without doing so, the appeal of Monzo (and others) will be a force to contend with.