Would they be thrilled, either parents or theater owners, that is an assumption you're making without any proof. I don't see many if any theater owners actually complaining that they can't sell more showings because modern movies are now longer than in 1937.
Also even at 90 minutes that is still an extra 7 minutes that wasn't in the original that has to be added to the story, thereby still making its not a true shot-for-shot remake. But this movie will be, based on reports, 110 minutes just short of 2 hours, making it only 27 minutes longer than the original. So they aren't going to be adding too much more to the story anyways, so yeah will likely still be more of a faithful adaptation than what you're thinking.