Kid invoker can already be bought for less than $10 today from dotagiftx. And you're not even buying the kid invoker, you're kinda buying the Angel of Vex set and getting the kid invoker for free.
Pudge persona might go the same route and it feels kinda weird to me how non-persona owners get the persona PLUS the doll of the dead cosmetic but persona owners only get the doll of the dead cosmetic. Basically the persona is free when you buy the doll of the dead set.
Seems like Valve intends for most battlepass personas to be re-released for free in future when you buy some future persona cosmetic, and they aren't really worth much in the battlepass, which I'm not sure is the kind of community impression they should be giving if they want to continue their record battlepass sales.
And I think something as simple as one unique piece (maybe arm slot or head slot or whatever) that original persona owners have that don't come for free might strike a nice balance in keeping the perceived value of the battlepass personas (because let's face it, without FOMO marketing, battlepass sales wouldn't even be a fraction of what it was in the past few years)
Source: https://www.reddit.com/r/DotA2/comments/11vzx6n/if_pudge_persona_ends_up_being_10_on_steam_market/