The Book of Abraham will fall first, then the Book of Mormon.
Right but this highlights the problem. As I said above, Mormons love to throw the Bible under the bus because the Historical-Critical Method significantly complicates the received narrative. Except, we know that even if Moses didn't write Deuteronomy, that the Deuteronomical law was a real thing. The Historical-Critical Method succeeds precisely
because the Bible is a complex compilation of texts from a wide swath of human history. Once that methodology is turned on the Book of Abraham and the Book of Abraham, the only reasonable conclusion is that they are the products of Victorian spiritualism cross-fertilized with frontier nationalism. Then what?
I appreciate the beliefs of e.g. Kish, and I can see the value in an approach where you say, well maybe this text isn't what it purports to be, nor what its author purported it to be, but that doesn't mean that this text is worthless. Okay, no problem. But TBM's aren't paying 10% of their gross because of the poetic or narrative richness of the Book of Mormon, they are paying 10% of their gross because they believe the Book of Mormon is what it purports to be and what its author purported it to be. The brutal fact is that the Book of Mormon, unlike e.g. Deuteronomy, is not what it purports to be, i.e. a real record of real history (refracted through the Urim and Thummim of culture and thousands of intervening years of redaction).
"Mainstreaming" may be a necessary survival tactic, but like Kerry Shirts said on that other board, LDS engages with real world big boy Biblical scholarship at its own peril.