Those goal tallies almost certainly are not happening. The plan appears to have been to tighten up at the back, because 40 in/50 conceded is very consistently lower mid-table over the years. The closest anyone's ever flirted with disaster on those kind of numbers was Sunderland in 12/13, finishing 17th and staying up by three points and goal differential while scoring 41 and conceding 54. That's a huge outlier.
If you look at the historical tables, it's when a club scores 35 or fewer or leaks 60+ that they can get shipped down. Whether or not that happens depends on just how pants the remaining teams at the foot of the table are. You can go down scoring around 45 if you're leaky enough (rare), or stay up on 28 (Huddersfield) if you're stingy and the rest of the league is dire.
Either way, the best thing to do is take the guesswork out of it, which is what it looks like Lampard and Thelwell are trying to do by stitching together an attack and tightening up at the back.