Well there's a difference between not being in the "Big Leagues" and being commercially dead. Moving 500,000 copies of a game would be a total commercial success if it was put together with a relatively small team. If you had a five episode game and moved each episode for $10 each you'd pull in $25 million. A smaller team could work with that quite well.
Well, for one, if you want to see how the genre is doing, let's see two things:
1) How much Tales of Monkey Island and other recent adventure games have sold
2) And more personally to your team, how many downloads Episode 1 (and then after all is said and done the other episodes of course) have had.
And $25 million, under a commercial license, would be divided amongst a 3rd party team and Activision--Which might not break even depending on the budget given. If 25 million is just for 500,000 sold, imagine how much Activision (which fully owns the copyrights and developer of Starcraft and thus doesn't share the profits with anyone) has made with Starcraft which is expected to sell 7 million. 500,000 to a company like them is spare change. And that's a maximum amount--I don't think any adventure game since the genre's peak has sold more than 1 or 2 million.
I mean, why do you think most major studios ceased to make adventure games by 2000, even though Myst was at the time the highest selling computer game of all time? Because compared to something like Starcraft, or Quake then, adventure games--
Quality adventure games, with all of the fancy things like a 1,500 page script (the original size of TSL if I'm not mistaken), hand painted graphics and backgrounds, quality animations cost a lot more than a game like Starcraft. Hell, it's why Blizzard abandoned their own adventure game.
Even If you go 3D, the point of having a commercial budget would be to have the best, or near the best 3D, right?--Not subpar or crappy 3D (in comparison to today's games)--If you're going to aim for lesser 3D or other high end tech stuff, there's really no practical need for a commercial license. I mean, if it isn't to have the best or near best that money can buy, than why have a commercial contract to develop 'official' games outside of simply having bragging rights or ego?
That's another thing: If you're going to get a commercial license in general, why does it have to be for dead franchises? Why not get a commercial license or even just go professional to showcase you own, original creations first? It would sound to me then like you're using beloved brand names to sell your own vision.