Sounds like better left for a browser plugin
It's an opt-in experiment, and at the end it's possible to a) be rolled in as a feature, b) spun off as an optional add-on, c) scrapped entirely.
Oh yeah, or d) taken back to the drawing board & re-engineered for another go-round.
The idea that it's appropriate as a plugin is in anticipation that they'd decide to integrate it like hello and pocket.
It's a feeling, there are all sorts of different browser efforts, FF just feels like we're getting to a point where it is drifting closer to the other browsers and getting heavier. YMMV.