If it lost its tax status, NRA would likely have to, and I would argue should, abandon all of its tax exempt activities, such as NRA Matches, Eddie Eagle, Hunter Ed, etc etc, and focus entirely on politics and lobbying. NRA-ILA might be the only thing that survives. But let's be honest with ourselves, the PAC was the lion's share of what NRA was doing. Participation in NRA-sanctioned matches has been dwindling for years, if not decades. No school district I ever heard of is using Eddie Eagle in their schools. So those tax-exempt activities are rapidly becoming inconsequential. There are other governing bodies, such as CMP, International Hunter Ed Assoc., etc. that can take over those activities.
Side bonus: if this allows more effective organizations, such as GOA and SAF to rise to the forefront of the battle, that will be a good thing. NRA needs to do some soul searching.