One of two things will happen -
1. Honda will make a moderate improvement, but that will be seen as a failure in the press.
2. Honda makes significant gains and the press get giddy, hype up 2018.
I do wish people would stop obsessing over update y will bring x amount of horse power. Until they address the issues with the ERS and ICE, the HP potential will remain just out of reach. It looks like Honda is getting to grips with it's various issues. I wouldn't expect too much out of Spec 4 at Monza though. Seems more like it's aimed at ensuring McLaren do well at less power sensitive tracks in September, leading to a bigger update.