I am working through Ken Schenck's Cosmology and Eschatology in Hebrews at the moment (I'm sitting in the library with the book open as I am writing this).
I just have read the introduction and it looks like it will be an interesting read.
While I am predicting that our perspectives on temporal and spatial dimensions in Hebrews will cohere more broadly (although I cannot guarantee any agreement in matters of detail), we seem to get there by different roads.
He focuses on the narrative and rhetorical worlds assumed and shared by the earliest, let's say, meaning-making community. I too am interested in rhetorical aspects of Hebrews, especially as it relates to how the author plays with spatial and temporal dimensions (often transmuting one into another), yet he gets there through Wittgensteinian language games with some Ricouer while I prefer the route of Bakhtinian dialogism (and, since we're talking about space and time and how they interrelated, the Bakhtinian Chronotope). Also, the narrative I rely upon is perhaps a broader story. It is the ancient near eastern narrative of creation, sanctuary-establishment, enthronement, and rest (not always in the same order) found in texts like the Enuma Elish, the Baal Cycle, etc., emulated and transformed by the Pentateuch, and, then again, reconfigured in the Songs of the Sabbath Sacrifice (placed on a heavenly realm) and the Epistle to the Hebrews (also placing the sequence in the highest heaven with Christ now taking the leading role). I do not see this narrative sequence as the "key" to reading Hebrews (I don't believe in any such key), but as one of many narrative (or we might say "mythic") patterns, albeit a dominant one that insinuates itself throughout the entire homily, Hebrews engages with and transforms.
As such, I also agree with Ken that the search for a monolithic background in Hebrews is a misguided one since it assumes an ancient world in nice and tidy little boxes whereas it is increasingly clear that it was much more interactive in its networks; I prefer to think of the homilist as appropriating and transforming many traditions, imagery, and narrative patterns with which he(?) interacts.
Only one thing caused me to raise an eyebrow so far. It is when discussing that strange passage of how Jesus cleansed the heavenly tabernacle (Heb. 9:23). Indeed, while this picks up on the most important aspect of the Day of Atonement ceremony (which is the purging of the sanctuary of the impurity created by the people; Lev. 16), the question remains: "why would the heavenly sanctuary need to be cleansed?" Ken's answer is that the author is playing with metaphors and we will run into difficulties if we push them too far...that the author was not picturing the cleansing of a literal structure in heaven (p. 8). That's fine on the literal point, but why would the author picture Jesus cleansing a metaphorical heavenly sanctuary? It does not seem to answer the question to me, but simply remove it one step away. Maybe the point is not that we have pushed the metaphor too far, but that the author, in fact, got caught up in his own metaphor and pushed it too far to the point that it broke down.
What will happen next in the story world of Hebrews's cosmology and eschatology?