First test nets have transitioned to PoS already. It's gonna happen soon.
Did they have a successful test? The last news I caught had 1/3 failures or something like that
They do bi weekly tests with the mainnet state and by now it's getting pretty stable.
I can't say anything about the absolute code quality however I think we are getting to a point where economic and community pressure forces them to take some risks
2015 was the originally announced date I think.
It was just part of the roadmap back then. It wasn't an imminent upgrade for which there are live testnet merges being conducted.
They've merged on the test net, so the August timeline is sounding realistic.