As we stand right now, I honestly think the best we can realistically expect is 8th as we've not yet addressed the weaknesses in the squad, nor have we cleared out enough of the journeymen clogging up the place.
Niasse, Kone, McGeady and Gibson all need to be moved on, maybe even McCarthy unless he starts to be more positive on the ball... Koeman will not accept sideways and backwards safety first footie. He wants positivity in possession.
If, and at this late stage it's a big if, we can land a top goalie, Mata and a quality striker to play with Rom, then 6th would be a significant improvement upon the rubbish of the last two seasons.
Anything below 8th and next summer will see Stones if he's still here, Lukaku and maybe others demand a move away... and recruiting for 2017/18 could be a bigger issue than this summer.