Yes, great idea - I’ve also had this problem before.
A 16 digit card number (PAN) is actually just a pointer to an account. So you can have multiple PANs all pointing at the same account. You can even have PANs without a plastic card attached.
So the solution is to let you generate a virtual card just used for online subscriptions. I believe the expiry date can even be set to decades in future. You could even generate a new virtual card for every new subscription service - letting you can easily cancel a service by disabling the card.
It’s definitely something we’d like to support.