I hope they really turn it around, the data we have at the moment is quite disheartening especially since the high dps of festerblight may solve itself next patch even without blizzard intervention.
As Mendenbarr said in his EJ post, unless another trinket comes next patch that gives higher than a 549 feather would, feather would continue to be our bis but this doesn't seem to consider a fairly big factor. Surely it is only festerblight's BIS and not normal unholy.
As a theoretical example, if in 5.4 a trinket came out that gave 7000 strength with 100% uptime, it would probably be quite good for normal unholy but because its strength is lower than feather's, it wouldn't for festerblight. This difference would allow normal unholy to "catch up" to festerblight in a way. I am not nearly as familiar with the sims as others, but I imagine that normal unholy is the more weapon dependent spec and this leads to my next point: weapon upgrades would also close the gap between festerblight and normal unholy.
Honestly not sure if this made sense i'm exhausted,l i'll try to reread later. Though I am pretty hopeful after seeing the most recent tweet.
If I had to speculate it would be that tricks would be modified to dynamically update and the unholy might nerf reverted. However I could totally see the strike change staying. It buffs both festerblight and normal, but it buffs normal more and brings it closer to that "high risk moderate reward" that is their goal.