Kill Bill (note: I'm a co-founder) provides payment routing capabilities, so you can integrate with multiple providers (e.g. Stripe + Adyen) and shift payment traffic to go through one or the other dynamically. This is very common in large b2c companies.

That being said, to your point, this still requires either a vendor neutral vault for the cards or to tokenize them in all of the vendors. Possible, but still hard to do in practice.