So now that we know Brigitte will be nerfed via the standard development cycle rather than the quick hotfix other broken heroes got (sorry Sombra, McCree and Bastion), we can assume this’ll be the same as how they treated the mandatory support heroes (Ana and Mercy).
So here’s my prediction: the first nerf will come and it won’t be enough. The next will be two months after that and still won’t be enough. The third will be enough and we’ll total five months of mandatory Brigitte.
Similar to the four month failures of Mercy and six months of Ana because Blizzard failed to learn from Ana and my guess is that they failed to learn from Mercy.