Wp9 is not on the cards yet, 8.1 is due out early next year, the fact that they have started the update number at 1 tells us we can expect a few of them. If it was 8.5 then there would be room, its not, there isn't.
Secondly, as wp9 is likely 2-3 even 4 years away, trying to guess the specs now is like trying to guess the Samsung note specs when the iphone 3gs launched.
I retract that last sentence. And replace it with this
I suspect that for a small portion of time in the future after a period of one week, but before a period of one million years, there will be various flag ship phones from at least one OEM that run wp 8 series software and have quad core processors and a 1080p screen. Please note this is not a factual statement, but one based on logic.