I think it would work the opposite way around.
Yes but arguably not same world. Though they have assed argued it was part of their 52 universes. I'm sure they would be much more willing to include Saint of Killers, or Arseface in an MK game with fatalities them Batman or someone in Canon DC
Oh yeah, definitely just pointing out WB owns the rights to both DC/Vertigo properties so I could totally see them do something down the line in games like MK maybe. *they already did in the New 52 adding Vertigo and Wildstorm characters into the DC canon)
Curious though,not the same world obviously but with ownage rights it wouldn't matter in this case or of course with someone else oking rights(like Todd Macfarlane's case with Spawn for example) then with guest characters that's kind of irrelevant you know as far as well continuity at least. For future, Even their DC other books aren't same world ie Watchmen, MK X(now) etc I could see them including one of those mingled with MK possibly.
Just same ownage property so WB could be like "yeah for MK 11 put in V or Rorshacas a guest character" this wouldn't surprise me.
I personally kind of wished MKU, Watchmen and Smallville Universe was apart of the New 52 as those other ???? worlds we've yet to know about I think there's 7 unknown worlds from the multiversity guide if you read that.
I pesonally would love to see also see Riddick in MK, his ruthlessness would fit in perfectly but sadly he's owned by Universal who I believe is owned by Disney or something, so I doubt that would ever happen. Although, Disney did allow WB to make the lego game Marvel Super Heroes so who knows?