I have no clue on how they intend to market it, just that it's on the board for Pontiac after the 1st year of production.
As far as I know, they could bring it over only as a DIV6 w/automatic or they can bring over just a GXP version with an LS3 and a stick.
The wagon will be considered a truck under current rules, and therfore actually contributes (based on sales, probally almost insignificantly, but still in a positive way) to boosting GM's CAFE for trucks even with a 400+ horse V8, so no telling.