My app, if successful, could conceivable have 100,000 users, who use it 10 times each, generating 1000 records each time, thus generating 1 billion int type primary keys. So conceivably the app could eventually generate enough records to exceed the limit of the int type (2B+).
Another feature is that most of these records would be effectively archived within 90 days.
GUID is overkill for sure, so the alternative is bigint.
Any suggestions about this would be appreciated.