The rumors that support for PZ ends "after the next pack" has been going around since the SA pack, with absolutely no basis, and we've had 4 packs since then. It's just baseless pessimism.There has never been anything other than silence from Frontier regarding future dlc since launch. Steam changed its system so that steamdb no longer gives indications of upcoming dlc - it’s nothing to do with Frontier and applied to all games on Steam.
Those rumours have very little to support them but official info from Frontier (as others have noted) demonstrates at least 2 more packs, probably more, given that they’ve hired new staff specifically for the game.
And….? It’s only just 3 months and the pattern isn’t very well established anyway, certainly not enough to say that it’s particularly late coming at this stage.