Impossible to tell without considering the effect of possible price drops especially on Sony's part.

It's realistic to think that without an other Xbox price drop Ps4 will continue to gain ground until Halo 5.

But what if MS drops price to 299$ at E3?

I also think that PS4 will get a price cut in time for the MGS5 launch on 1st Sept and if they cut to 299$ MS will likely lose ground during the holiday season as well, Halo or not.