So, essentially, Backgrounds would be pre-generated Skill progressions, while Themes would be pre-generated Feat progressions? Sounds reasonable, although hopefully they won't fall into the "lousy but flavorful" trap that pregens tend to fall into.
This could also be used to effectively support the "3 pillars" design. Background (Skills) would be dedicated to Interaction and Exploration, while Theme would be dedicated to Combat. I'm of the opinion that significant tradeoffs between combat and non-combat in a game like DnD is a bad design, so making them parallel choices would be a good thing.
We might have a Rogue who takes the "Burglar" Background, which would give bonuses to urban stealth, lock-picking, and acrobatics, and the "Lurker" Theme, which would be about making stealth viable in combat. And a Ranger might take the "Wildling" Background, which would give bonuses to stealth in nature, tracking, and endurance, but might still take the "Lurker" Theme.
I'm also picturing Skills looking a lot like 3.X/4E Feats, in that they'd be free-form blocks of mechanics, not just points put into a predefined set of skills. So a lot of non-combat feats from those editions would just become Skills.