To me, it's a no-brainer. Tiffin's Allegro Bus sales greatly skewed towards the tag axle chassis once they were introduced. I'm sure Winnebago will boost their sales accordingly once they bring one out.
Rvers who look for the nicer diesel pushers want amenities and room. The 42-43' floorplans give you that room. Plus, a typical 40' upscale pusher may have adequate CCC but it's dangerously closer, or even over, on the rear axle weight. All those quad slides, ceramic tile floors, washer-dryers, dishwashers, solid cherry cabinets, and solid surface countertops really add on the weight and most of it is over the 20,000 lb rear axle. Adding a tag axle gives you an extra 10K of capacity and allows the coach builder to stretch the length a few feet. Also, driving a tag axle is a dream compared to a single rear axle. Most owners that you talk to won't go back to a single axle after once having a tag.
I think Winnebago will do well with offering a 42-43' tag axle unit as long as they offer it in a Vectra class or better. I'm just surprised it took them this long to figure it out.