I agree with above -- if the parks open by mid-July, I doubt they will further extend the ticket extension. If the parks remain closed into the latter part of the summer, it's possible. But really, it's a big unknown at this point.
Specific to the OP - with a partially-used ticket, which is really an anomally for WDW to carry that forward -- if you really won't get to use the remaining couple of days before mid-December, I would wait until sometime after the parks have re-opened and call to plead your case. The 2 days isn't likely to get you much as refund -- maybe $20/$30 per ticket, depending on when you bought them. So I'd also consider whether it's worth the time and effort of pressing for an exception.