Great post
Since I don't really have any modding ability, I'm not really qualified to offer an opinion on the feasibility of creating a mega mod a la GWX. I will say, though, that I think this is the logical and maybe even the essential next step for SH5. It's been out for three years now and despite all the hard work of the community and the excellent information about how to create a harmonious mod soup, there's still nothing approaching a mega mod. When I first decided to take the SH5 plunge after playing SH3 + GWX for a long time, I was intimidated by the sheer number of mods I would need to make the game playable/fun. Even with sobers' help, installing something like seventy mods is not an easy task, at least for me.
I'm not saying we need a massive, all-encompassing project like GWX or LSH3 just yet, but the community could really benefit from moving in that direction. It would level the playing field, giving a larger number of people access to a stable, easily-accessible solution to the bugs of stock SH5, while hopefully attracting more players (and therefore more potential modders) to the game. Finally, I think it would help modders in the long-term by refocusing their attention on the major problems that have yet to be solved.
I'm sure it would be difficult to get a project like this off the ground. Probably the biggest difficulty would be organizational, getting everybody on the same page, as you said. That's actually one of the main reasons I started the "community projects" thread. In addition to being a useful tool for modders, it might also serve as a litmus test for the community's desire for large cooperative projects.