I think they scrapped it. LN makes tongue & groove planes, which may be the remnants of the plow plane concept.
On the topic of combo planes, I almost snagged a Paragon multiplane earlier this week with all 40 blades. Damned if I didn’t see the ad on craigslist before several others did. The Veritas is the only game in town for brand-new plow plane/combo plane products.
Derek, I also think they may have scrapped it. I know the tongue and groove planes were around before they started talking about the plow plane, so not really sure what happened. After the first rumors and pictures about a year ago, there has been no sign of it.