Depending on how the 8 looks and what it's got standard kit wise then a runout 7.5 might be ideal.
It could be, but on the other hand buying one a couple of months before the Mk8 rolls into town will see your depreciation sky rocket.
Just depends on how you look at your cars I guess, personally I have a car for a few years and the total cost of ownership is important to me - so a massive drop off in resale value is a big thing for me. Far more than getting a few options chucked in.
Its irrelevant to me in this case though, I have my current Mk7.5 until July 2020.