Franchises work like this. An owner of an intellectual property (lets take the Wheel of Time series for example) has the ability to sell the rights to certain mediums at certain prices. Typically the IP comes from a media that they are totally qualified to do, in the WoT case, Robert Jordan and Brandon Sanderson has the writing aspect of the series totally covered. But the books are really popular, and people really would love to watch a movie or play a game of Wheel of Time.
So instead of opening up their own game studio, movie studio, bobble head production line, they sell the rights to WoT to another party so THEY can go make the game. Lets say they sell the WoT game rights to me (Which I would happily do). Now it is my job to create games since I just forked over a boat load, but I don't have the development capacity to make a PC/DS/PSP/PS3/360/Wii titles efficiently, so I use my money to pay other people to make the game for me. These are production houses like Activision, SEGA, and Capcom. Often they also have some internal developers too.
The amount I paid for the franchise and the amount I invest in the game developers is going to be LESS than I expect I can make off the franchise. There's a lot of fuzzy math behind the calculation of (DieHardMarket + CasualMarket) x (GameQuality-Cost) x msrp = MaximumProfit but it basically boils down to the fact that no matter how terrible you make a game, a certain number of people are going to buy it. Now, I am not advocating to put terrible games on the shelves, but because of this buying power you have, magnitudes of people will be playing your game while thousands of other highly funded developers toil in obscurity.
So this is the gift you've been given developers. No matter how terrible you make the game, people will buy it, probably a great many people. So now here's the great responsibility to come with your great gift; you actually have to make a good game because your marketing has been done for you.
Its freeing that you don't have to worry about getting the word out there about your game like many indie devs. It is also immensely stressful, with a limited budget and a hundred voices yelling at you to create a game thats the opposite of the other voices, but its got its own reward. You are going to reach a huge audience with a design of your own making so do your best and enjoy.