Regardless of how 2019/20 pans out it neither proves that sacking Hughton was a good decision, nor does it prove it was a bad decision.
If we finish 10th under a new manager, there is no way of knowing that we wouldn't have finished 9th under Hughton.
if we go down in 18th position under a new manager, there is no way of knowing that we wouldn't have finished 19th under Hughton.
We won't have the benefit of assessing the new manager under the same conditions as Chris Hughton, so there is no way of knowing who would have produced the better outcome.