Once your I-484 gets approved, you are an Legal Permanent Resident. PP Stamping is an administrative step, so that USCIS can produce a plastic card.
USCIS can revoke I-551 in only certain circumstances...
1. If your application was later found to be invalid/fraud was involved in filing
2. You commit a serious crime
3. You violate requiremts for your legal stay (staying outside the country for more than 6 months without applying for an extension)
So, don't worry... Anyway, once your I-485 is approved, you I-94, EAD, APs are all invalid...