Personally, I'm thinking 40 issues at this point. I just can't see Lemire wrapping it all up in 8 issues.
Agree with you though regarding his creator-owned work. Sweet Tooth is far, far, far better than Superboy, though I'll admit that a large part of that is that I'm not wild about Gallo's art and even less wild about Grant's colors.
Animal Man and Frankenstein look nifty though, and closer to Lemire's strengths.