Looking at some screenshots from youtube video it looks like the att/def level will still be present in pes2018.
Would love to believe that Konami are capable/willing to give us a game with an advanced enough AI that attacking levels wouldn't be necessary, but I don't see it anytime soon.
Just play PES 16, and see what the CPU team does in the final 10 minutes down 0-1. They have the same urgency as if they were up 2-0. Until the tactics are advanced and fluid enough, attacking levels are a necessary evil in my mind.