I've actually been thinking about this lately.
While Midgardsormr does seal the Blessing away, and the Ascians make note of no longer sensing the Blessing...
I wonder how much of that had to do with Midgardsormr's actions and how much has to do with something we learn a bit later - that Hydaelyn has become incredibly weak, so much so that she needs Minfilia to even manifest properly to communicate with us in her own realm.