Bitmain is already mining with Asics ETH. That's a fact.
Why??? Because it's impossible to move 8.000gh/s within 2 hours.
if we consider that normal people have 1 6gpu rig about 180mh/s, That's like saying 44.444 6-gpu's mining rigs were switched to ETH in two hours. That's impossible. Unless you are using ASICS.
Do you want another argument???
8 GHash for Ethereum is well within the range of NORMAL LUCK shifts, there is no need for "44 6-card GPU rigs" to have been brought online in 2 hours to account for it.
It's only about 3% of the current total network hashrate after all.
AUTOMATIC PROFIT SWITCHING mining rigs could account for a lot more than THAT in less than 5 MINUTES - or a single medium-sized Nicehash order starting up could account for it in less than *1* minute.
Watching short-term variations and trying to make something monumental out of them is a fools game.
Casper won't kill ETH mining immediately - that's the "1%/99% first step for TESTING PoS" that *MIGHT* finally go live in a few months if they don't have any MORE delays, making it very unlikely ETH will move to full POS before the end of the year even IF there are no more delays.