Haven't played any ranked this season so can't comment on that. Changes will probably push dive comp more in ladder compared to last season at least. Seen a lot of dive comp in quick play though when playing with gaffers but that might just be because people like to DPS and its QP :/
I'm pretty sure that has to be because of QP. If you check out the stats we know about S3 pickrates:
A lot of the core dive characters don't get spikes in usage until they are in M/GM. I know this is all of S3 so yeah, but anecdotally even post nerfs people just cling to the safe tank and 2/2/2 line ups. If you go to the bnet boards (yeah I know) even the higher ranking posters (diamond+, top 10%) are all still very convinced they are trapped in trip tank hell and Ana is the end all be all goddess.
They need to find a way to get people to explore other ways to play the game, and a lot of it comes down to having a bad UX on top of very unclear balance to people that aren't extremely literate in the game :T
The fact that a lot of this makes some sense if you are literate in the game while people say "lol Blizzard balance" speaks volumes for why they are looking at making these changes. They gotta start steering their general playerbase into some of this stuff.
It's too late for D.Va players though. That was an astronomical fuck up.