Very interesting. I think the pitch counters in both HollowVine and Dredge load more of the value of your deck into your opening hand, and having strong early hate-bear options mirrors this quite a bit.
It feels to me like Pitch Dredge showed that there was room in the Dredge archetype to load in almost any package you wanted. That point was driven home by Zias' Shops/Dredge hybrids, and now we're looking at massive hybridization of the Bazaar-as-creature-engine concept. Admittedly, in HollowVine decks the Bazaar doesn't serve quite so squarely as a graveyard engine in particular, but it feels like a close cousin to me.
My personal preference is always to maximize consistency if your deck has sufficient power level. I would be interested in seeing a version of the HollowX archetype with artifact-based lock pieces, because the mana for that can be much more consistent (one mana source being sufficient for almost all lock pieces). Granted this would weaken Once Upon a Time quite a bit, but perhaps it would be worthwhile.
The only cards that seem to have any real potential are Underworld Breach and Soul-Guide Lantern.
Breach is very exciting, although we'll have to see how widely it gets adopted.
Lantern to me doesn't feel head and shoulders above the other options, just a nice tool in the toolbox alongside Crypt, Relic, etc.