1. Does such a beast really exist?
2. My goal is to ride old, poorly maintained asphalt, flowing singletrack, and some hilly routes around where we live, as well as some general-purpose urban riding.
3. I'm not interested in drop bars or carbon. Flat bars are a must; aluminum is fine, but (affordable) steel would be really nice!
4. In terms of geometry, durability, and equipment (and upgradability,) how far from (or how close to) a true XC bike does a quality, well equipped hybrid fall? (Think along the lines of the alloy Trek FX gen. 4 or Trek DS gen. 5.) Will either of those types of bike do for my intended purpose instead?
5. Is it really a flat-bar gravel bike that I want but I just don't know it yet?

I'll ask more questions as they come to mind or as inspired by the replies.