A blockbuster game like GTA V or Black Ops II can take more revenue in their first 24 hours than many movies over their entire cinematic runs and follow-up DVD and Blu-ray sales. This isn't new, revenue from games overtook Hollywood in 2009 and the gap continues to widen.
Not all games sell gangbusters but if you have a great selling game, it's a licence to print money:
Minecraft - 49 million slaes (all platforms)
GTA V - 32 million sales (360, PS3)
COD4:MW2 - 28 million sales (360, PS3, PC)
GTA San Andreas - 27 million slaes (all platforms)
COD:MW3 - 25 million sales (360, PS3, PC)
Gran Turismo 5 - 10 million sales (PS3)
This is why Sony are dropping low-margin utiliarian markets like PCs but remain in the console business but are dropping low-margin markets like PCs. And it's why Microsoft won't just abandon it lightly. Even when your are only the platform holder, you're picking up licensing royalties.
License fees are nice, it's what made PlayStation such a success. Of course, if you're signing exclusivity deals, marketing deals, or just desperate to get big games on your system you might have offered a big publisher like Activision or Rock Star a significantly reduce rate. It also really only provides a big pay-off when you're #1 with a bullet, like the PS1, PS2 and Wii. MS added a sweet wrinkle with the Gold membership fees that provided a torrent of free money, but unfortunately they kept those profits hidden in the division where all their worst money-sinks go to die.
But you know how Nintendo really made it through the N64 and Gamecube days (aside from the GBA and DS)? They were the number one publisher on their own platform and their biggest games all sold huge numbers where they kept ALL the profits. Similarly, during the PS3 generation Sony was publishing 15-20 games a year where they, again, keep all the money. Microsoft doesn't have the first party stable to really sustain a distant 2nd finish profitably. Gold membership won't do it either if they end up losing 1/2 or 2/3rds of their paying members and continue to give compute time on Azure away for free. And while they do have a safety net, it has nothing to do with games so the question is again, why bother?