What IAS does a 421 show at altitude? We can (maybe) assume it will hit the water at approximately that speed since it was trimmed for it. Hopefully a survivable speed.
Sorry to hear this too, it sounds like if the USCG was on scene there is a chance for survival. You are definitely unconscious at 25,000 feet, but not dead right. How long does it take for consciousness to regain once you glide down into altitudes with enough oxygen? If the descent was slow enough, possible that the pilot regained consciousness and was able to at least slow the plane before ditching?