I'm not sure about that tbh. RZA is certainly more used to and willing to deal with the headache that is the Wu (the jealousy, brotherly bickering, etc) but I could see other people putting out a good album with the members minus RZA. I'd take an Alchemist/Wu album for instance, he could certainly pull it off. You'd get dope production, dope art, and a cool video or two - just like every product he's done in the last 3-5 years.
I could also see Apollo Brown making a dope Wu album.
Ultimately the issue would come down to costs. Getting everyone's verses and accounting for delays would be expensive. But if someone was willing to take that risk I think the Wu could do something decent. Give me some dope art, a badass vinyl, throw in some posters and something weird/cool like a short Wu anime or documentary. Package it well like RTJ2 or Czarface and fans would buy the shyt out of it. It won't go gold but that vinyl would constantly sell out.