All I can think of is that they will compensate on the next patch notes.
I dont think blizz is going to walk away without sorting this out. They nerfed this set bonus because they knew we were going to ignore t13 4pc because it was CLEARLY BETTER than t13.
With the current events, It's almost obvious that they are going to compensate in some fashion.
How they are going to compensate is another question...
Lower FE cooldown?
Flat DPS increase?
I'm sure they dont want to make the mistake again of 15% of the dps coming from a tier bonus so I imagine it will be some class changes.