The Acquisitions Directorate (CG-9) web site has a profile of the project manager for the Offshore Patrol Cutter program (CG-9322), Capt. Douglas Schofield. Sounds like he has first hand experience with the problems of continuing to run the legacy fleet.
There is also a short piece by Master Chief Petty Officer Brett F. Ayer about how platform requirements are determined.
Chuck Hill's CG Blog 
“The parts for these big, expensive, and now frequently obsolete systems are often not available, leading to problems maintaining the fleet.”
If the Deepwater program was successful many more of those assets would be replaced by now making that statement much less relevant. That was the reason for Deepwater in the first place. ICGS was under a program wide guaranty to do just that. Mission performance should not have degraded.
Master Chief Airhead (yes, that is what the officers in the building actually call the guy), is hardly an authority on anything. Guy has been avoiding sea duty his entire career.