According to the article, it's not a fatigue issue - it's an inability to withstand limit loads issue (so yes, at least a theoretical back end falling off issue). Due to improper shim thicknesses installed during joining of the sections, installation of the fasteners for the joint causes localized pull-up loads and stress to be introduced in the composite material at the highly stressed areas of the joint. The surface discontinuities then apparently add stress concentrations. The joint strength with these conditions is apparently insufficient to withstand one or more of the applicable design limit loads. I don't know what flight conditions set the most critical limit loads for the section 47/48 joint, but gust loads, engine failure on takeoff, and hard landing touchdown are likely candidates.