Mariano will have his number retired. If Marmol does something similar, so will he, but that's going to be very hard. Mariano's number is already retired. Really though, the next number I see the cubs retiring is 21. Probably not within the next 5 years, but after that I'd assume they'd come around and retire it. As for current Cubs - it could be anyone. If someone gets a World Series winning hit anytime in the near future they'd probably get the honor just for ending the drought.