Exciting news! It will be interesting to see the modern GW take on SciFi skirmish rules (and if people don't like them so much, the Necromunda Community Edition is still strong!). People on YakTribe have already floated the words 'Retromunda' and 'Neomunda'

On the topic of scale comparisons, I think it was inevitable that the metal gangers would be noticeably smaller, like with WH40K 2E-era miniatures. I suspect the trend started earlier than people might think, though, with such friends as the plastic Imperial Guard box sets (Cadians are pretty huge!). I imagine they must have made them at least roughly in scale with the cultists and Genestealer cults, though photo comparisons I've seen haven't been quite convincing yet. But of course we do know that GW has hardly been historically consistent with scale: not only with Epic, but with regular 40K stuff too!

Of course, while it might be nice to have matching-ish scales for the new GW miniatures, there's nothing to stop people converting/kitbashing miniatures, or using any of the excellent alternatives out there.