We'd lose a couple of thousand from attendances who would be hard to get back. If we're only down for a year some sponsors might stick but some would go. Corporate cash would take a major hit.
That would mean looking for savings, particularly off the field, but there'd be no pont running a full SL strength squad and some players wouldn't want to spend a year in the championship either.
Not an utter disaster but it would take us a few years to recover to the point of being competitive.
As for the rest of SL they'd lose attendances and corporate, and god help SL negotiators if they're working on a new TV deal.
But never mind, the extra few hundred Leeds away fans will save the championship. Not.
I suspect whilst some fans of other clubs might be happy if we go down, those running other clubs will think the opposite.