All those franchises you mention pale in comparison to GTA. Furthermore, extra missions, islands etc are more significant than extra songs/multiplayer maps. Besides, until we have real evidence, we are all just speculating on the content of DLC. Nevertheless, 50 million dollars is a substantial amount, and I think the extra content will reflect that investment. Like I said earlier, MS didn't advertise DLC, which is a huge oversight, and only makes sense if they plan on doing so later.