Prestiging is rewarded with vosh and prestige skins. These skins are for the weapons in the core lineup of the perk you prestige. But survivalist doesn't have a core lineup, he's mostly about borrowing. He has his own knife, and the freezethrower. The double prestiging we can already do gives us prestige skins for both of those. So when we triple prestige, what's left to reward us with survivalist prestige themed skins for? Any of the weapons survivalist gets benefits for, which is all of them. But to not have two prestige skins for the same weapon, with just different perk icons on them, it shouldn't be a weapon from another perk's core lineup. And it may as well help hype up whatever's new in the same update.
So it makes sense that there would be a survivalist prestige themed Tommy gun skin, even if the Tommy gun is a SWAT and/or Commando weapon, and has no association with survivalist beyond that which every other weapon in the game has.
The other upcoming prestige skins are for Tier 2s for all the other perks. Survivalist's prestige skins are already not following conventions, having went from knife to T3 when every other perk went from knife to T1, so I wouldn't take this as an implication that Tommy will be T2.