Provided GF has enough 2-3 year FO's who came with some experience it should not be an issue. Last I saw (from a friend still at GF) there are about 70 FO's with 3 years plus time at GF (less a handful of career FO's). Each year that passes with less than 70 upgrades means there is always at least some supply of guys that should be upgradeable.
So the issue is in how fast aircraft are arriving. If each a/c requires 5 or 6 captains that means it would take well over 10 new aircraft in one year to start depleting the available FO's to a critical level.
...of course, this assumes no one is leaving in large numbers
I would guess that CC will be able to keep his word.