This is common, actually. I would argue that Rugby is at varying levels of un-sustainability in England, Scotland, Wales, Australia and South Africa (at least in a form where most top tier professionals play domestically). There are also warning signs in NZ who are, due to location and size, somewhat dependent on Australia maintaining a professional presence.

France seem to be the only country capable of running a competition in the black (though many of their teams have wealthy benefactors helping). The Japanese sides are all liabilities for their corporate owners who maintain them as a cultural obligation. The emergence of France and Japan as high salary options has more or less destabilized the rest of the rugby playing world.

I reckon on the mid to long term South Africa join the 6 Nations, which is the only reliable source of fan driven funding outside the RWC, and rugby everywhere else withers as fans turn to more commercially driven games like NRL in Aus or Football in Europe.