The answer to the question everyone has been asking.

[Kurando]

This is hardly the case, and the Final Fantasy franchise has quite literally kept their whole rig above water for years now. If FF plummets, so does SE baring another hailmary success, which they are also known for. .

Perhaps internationally, but locally in Japan Dragon Quest is actually bigger than FF. In the off chance everything goes to crap and FF is no longer the money bringer, SE could probably just return to its home market with more DQ installments. Although in recent years DQ has found much more fame in the West, so that could be their saving grace, not to mention other titles like Nier have done really well.