Changing Payment Gateways in Pro Sites


I recently changed default payment gateways from PayPal to Stripe in Pro Sites. I still have both active, but only Stripe is available for new signups.

If any of my current users, who are on the old PayPal gateway, make edits to their subscriptions, do they remain on PayPal or will they switch to Stripe? I am just wondering how the recurring billing is handled if it switches.