I'm hoping it will be somewhat more violent than Oblivion, but I at least don't expect to see it be less violent.
Considering that Oblivion's sales didn't seem to drop even once its rating was changed to M and Bethesda seemed to have no qualms with making a game that would definately get an M rating with Fallout 3, I'd say Bethesda doesn't actually object to games getting rated M. And in any case, the problem with that sort of thing is not so much that it would raise the rating to M as the fact that it would likely spark horrible controversy and potentially cause the game to be banned in some countries, as shown by the fact that even though Fallout 3 and New Vegas are both rated M, for good reason, I'd say, neither of them have killable children. I'd say Bethesda would be able to safely add children as long as you can't kill them, though whether Bethesda WILL add them or not waits to be seen.
I do certainly hope for more violent gameplay than Oblivion. At the very least, I'd like a plausible amount of blood, that, like in Oblviion and Fallout 3, sticks to surfaces, and unlike in Oblivion ACTUALLY DOES SO LONG ENOUGH TO BE NOTICABLE. I don't expect the blood decals to stay around permanently, that would just slow the game down and, quite frankly, is unnecessary, but when I can see the blood vanishing right before my eyes while my enemy is still alive, then that's long enough. I'd also like to see some actual visible wounds on characters, really, just some wound decals would be good, as long as it makes it so that people you just hacked to death with your huge ax don't look like they could have just been poisoned, I can live with it. I don't want something as extreme as Fallout 3, though, not that I have any qualms with the occassional dismemberment in my games at all, but the ease of which limbs can detach or explode in Fallout 3 is just a little excessive. Now, Fallout just wouldn't be Fallout without gratuitous violence, but for the Elder Scrolls, I'd rather the focus be on making combat feel realistic and brutal, sometimes in games the violence can be so over-the-top that it becomes funny rather than disturbing, and that's really not what I want from the Elder Scrolls. I wouldn't object to the occassional dismemberment, but it should happen only rarely and if the attack does enough damage.