Eclectic Light does it again going deep into High Sierra where no other tech writer seems to go. Lots of writers have been complaining about the removal of app syncing in iTunes 12.7 but nobody seems to know about the replacement:
Apple’s answer, I suspect, is in the new Content Caching feature in High Sierra, although that doesn’t appear to be offered as a retrofit for Sierra. Apple hasn’t yet provided full details, but what I think is intended is that those with multiple iOS devices use their Mac as a local app and update server…
In many ways, this is a much neater solution than poor, overburdened iTunes has been.
If you used iTunes app syncing at all do yourself a favor and read the Eclectic Light post.