The thing that kind of irritates me about this whole "Gossam Commando" movement (and I'm not referring to anyone in particular) has to do with the idea of the Commerce Guild/Trade Federation/Corporate Alliance/Techno Union/etc in the story of the films themselves.
It's well established that the reason the TF uses Battle Droids to begin with is because they're cowards and wanted troops that would listen to every command they gave without question. In other words, a total automaton military force. The makeup of the Separatist armies which combined all these forces in AOTC/CW cartoon/ROTS was, as well, a complete automaton army, although at that point there was a bit more in the way of self-motivated droid intelligence (Grievous' MagnaGuards, Super Battle Droids to an extent, etc). The impression given is that the companies that make up the Separatists/CIS are selfish and more concerned with their own species safety, so droids are an easily-produced and easily-expendable surrogate that keeps the species behind the military commands safe from harm (theoretically, since they all get killed by Vader anyway).
That's why the Gossam Commandos bother me, conceptually. To have a bunch of Shu Mais running around with oversized cannons, putting their own lives on the line and contradicting their entire profit-driven motivation, is really at odds with what has been established in the films as their raison d'etre. Plus the Gossam Commandos look silly to me.
After all, this is set to be a Target exclusive Battle Pack, right? And Hasbro has stated that the exclusive Battle Packs tend to get new offerings instead of the wide release Battle Packs.
I'm thinking along these same lines, Nick. Hasbro made a point of saying that the mass-release BPs will be almost completely repacks with slight retooling, while a bit more would be put into the exclusive BPs (concept-wise, anyway) since they would not need to appeal to such a wide audience. A Gelagrub could work if done in a "pack-in" way, or hey, there's no real rule that says they have to fit in the traditional BP box (maybe they could do a "Screen Scene" style box like the Geonosian War Room/Jedi Council sets from 2003). Still, it would be possible to fit a scale-fudged Gelagrub in a slightly wider BP box, but it wouldn't be displayed in an "awesome" way.
If they did go that route, here's what I'd expect:
1 x Aayla Secura (slight repaint of ROTS figure)
1 x Commander Bly (hopefully correctly painted ROTS figure)
1 x Felucia Clone Trooper (repack of Evolutions Felucia Clone)
1 x Felucia Clone Trooper (repaint of AT-TE Gunner, specifically for the legs, so he can ride the Gelagrub)
1 x Felucia Gelagrub with saddle
If they wanted to be really nice, they could just put the Tank Gunner legs and a soft goods kama on the Evolution Felucia Clone, but I doubt they'd go that far with this set.