I mentioned something similar in another thread (Monzo to be your 'one card')
If you think about Monzo as a platform rather than an account, and add accounts through Open Banking APIs and then consider the hot coral card as the way that Monzo (the platform) rather than Monzo (the current account) operates, then you potentially get somewhere interesting very quickly…
(On a semi related note, did I read that a Curve co-founder now has a senior role at Monzo?)