Batman would be a top 10 ten book and sell in the 80-100k range. Because that's just Batman now.
If they put him on Green Arrow, Question, etc. it'd be the same as Superman. You'd hit high numbers on the #1 and it'll level off at somewhere in the 35-40K range. Young Justice is popular, has a TV show, it's Bendis' sweet spot in teenage characters and it hasn't been controversial at all, if anything it's completely fan servicey bringing back Bart, Conner, Cassie & Tim and it's selling in the low 30's last time I checked.