I agree, Chris. I think there can still be a future for sandbox games, but I think the GTA 3 variety of them is going to quickly die. Dead Rising (I think that's what you're referring to), is a great example of how to broaden the genre as well.
There are plenty of themes that can be sandbox in design, and still be directed and interesting. I think if GTA doesn't change its tune, Take Two is going to be acquired by a bigger entity, and who knows what will happen from there.
RTS is definitely a candidate for deathwatch as well. StarCraft II was a decent enough game, but it's definitely not enough to keep the whole genre going. I blame this in large part to the decline of PC games. I think with peripherals like the Move and Kinect and the power of the PS3 and Xbox 360 respectively, that genre can continue to survive, albeit in a modified manner.
I'd like to see the next generation of home console embrace the Mouse and Keyboard as a viable control option so that any game type that once lived on the PC can also live on the home console without much tinkering. Maybe that's wishful thinking, but since when is control option a bad thing?