I think the market for a factory built reasonably priced 3/4 ton 4x4 cargo and passenger vans would be pretty good.
Think of all the contractors, ski resorts, mining/utility companies in snow and mountain country that would buy them as well as expo types.
It seems like the Titan/Armada Nissan 4x4 parts would be a pretty easy swap?
By good do you mean maybe selling 20,000 units? A 4wd NV is still a very specialized market, don't get me wrong I'm the expo type that would love a 4wd NV, but I'm young and getting by with a 13 year old pickup that is paid off, so not looking at getting a $30 to $40 grand vehicle anytime soon. In the RVing world that is a bargain but having a custom camping interior would drive the price of that rig well into the $75 to $80 grand territory, still a bargain in the RVing world.
And Yes the Titan and Armada parts should swap with minimal effort (F-Alpha platform; Frontier, Titan, Xterra, Pathfinder 05-12, Armada and Infiniti QX56). Frontiers and Xterras have been doing Titan swaps for years and I just put a transfer case skid on my frontier off of an older first generation Pathfinder. Got to Love Nissans, the few changes in decades of production. Makes there vehicles a little Spartan to start with but not that bad at the parts counter or pick and pull junk yard for the used car market.