I'm not sure how meta-magicking a low level spell would get around this change to spell saving throws.
Twinning, Repeating, Quickening all let you deliver more doses.
Chaining lets you share the pain across multiple opponents and grind for that 1.
As DCs don't matter, the barrier to metamagicking a low level SoD is gone(crap DCs for your level)
Combining Quickening with one of the others lets you provoke more saves to kill.
It's inefficient, but then the normal ways of making SoDs useful are similar(spamming to force a failed save,debuffing before putting the nail in the coffin.)
And as JaronK said, SoDs are just a hair above direct damage in usefulness. And the Fighter and Rogue are better at direct damage than casters.
The best spells never needed saves anyway, though direct damage and SoDs get torpedoed, so tactics remain mostly unchanged.