That's the greatest thing about the jump from Source to Unreal. The ability to scale and do modular asset structuring so much easier. On the Source engine you couldn't even scale models in-editor.
On Unreal, you can literally make a complete forest out of 3-4 different tree models.
But yeah, that would definitely be interesting to feature such a claustrophobic map - the game play would be dramatically changed. I'd be interested to see how it'd play out.
yes.. dynamic scaling is about the most exciting thing with new generation engines.
as for citish level I think you could integrate enough large boulevards and open spaces (occuring for some purpose of course) that you could integrate the dinos and let them roam as well. .. would have to think through a doable design.
a large mining complex always pops into my head. with large processing buildings big enough for old trex to run through but alot of minor paths for characters to navigate to keep safe. tunnel systems below terrrain we could do as well and always add an extra path to and from objectives that is unexpected.