Is is possible to change email address without losing the aging related to the account ?
No, it’s not possible.
At least for the payment methods that require e-mail that I know of.
Confirm, no details of the saved payment methods can be altered in any way after having created them.
Every data of those account is used to create the payment method’s hash, which in turn is used to verify its age and signed status, so altering anything would also alter said hash and its status.