First two were matte-color Carapace kits. The Second two were Copper Metallic Carapace kits. I predict that the next two will be Chromed ship kits, and the last two titans; Gold ship kits. I agree that this is probably going to be the Cutter's turn, but what of the last 3? Maybe Hazard Kits? FDEV have followed this pattern before in cosmetic rewards; ex: the Brewer Corp Decals depend on your level of participation in the CG, but it was available as white, copper, Silver, Gold.
I agree that it'll likely be the Cutter with a reworked Carapace kit, but I think we might see a different color used. The first two Titans gave us the bleached, and the next two gave us rust. I think we'll continue to see that progression as part of the "increasingly more prestigious rewards" line ooFDev gave us in the beginning.
I wish fdev programmed npcs reacting to your livery and/or ranking in some way, like pirate starting to scan you while you mine, noticing 5 star titans, triple elite and dead titan parts all over you, stopping mid scan, "sorry for bothering you commander, I'll be on my way" then jumping out, or a custom welcome before you dock according to livery or faction ranking. Then again they still treat you like a random visitor in your own fleet carrier, so I'm asking way too much.
Nice bit of speculation. I would not bet against you on this one... ;) Though I am not a fan of sticking bits of dead goid on my ship or rust personally... But they are free... So I can not grumble ;)