During 2016, Ethereum popularity with new peoples and a younger generation has brought millions of new dollars, euros, pounds, yuan, yen, roubles, etc into crypto-sector.
A certain minority of large GPU miners, store there mining profits in Bitcoins or cash out.
A lot of that new cash, has gone into double spiking the Bitcoin price this year - so Bitcoins real cash-floating price is around $550, but Ethereum has pushed it up to $700 per a coin.
When ETH goes to Proof-of-Stake, there will be no more extra cash support the Bitcoin price and it will move downwards to a more cash-realistic level.
Already a known date when the shift to POS?
Nope, it is being kept under wraps.
Naturally, when the date is announced: there will be a big price spike if it's really soon or big price drop if it is really far away.
Lot's of short-term speculators will messing up Ethereum's loyal long-term investors' private investment schedules.
I'd guess, the the date of Proof-of-Stake is too financially sensitive to be announced this year.
If I cant mine it.. I wont use it.. POS is just getting the rich richer!