I would think it would have to be closer to the Wax and Wayne books to fit them all in that period, but maybe he'll see it as more of a "main series" and want to push it to 200k. I didn't actually realize how low the W&W books until now though! I felt they were lighter tone and scope wise but didn't really recognize the length.
Well of Ascension's weaknesses are probably due to Brandon still being a newly published author so I wouldn't worry too much about repeating that problem.
I'm gonna go ahead and speculate now that Brandon needs something to happen in Mistborn Era 3's finale before Stormlight Era 2 begins which is why he wants to push them all out in a row. He's left himself in a tight spot if that's the case!
The batman villians all seem to be one big joke that batman refuses to laugh at - SantaRPG