As per Apple Developer Document, APFS will become default file system for macOS 10.13 and later. Should I presume that pre insatlled Mac will come with case in-sensitive version of APFS like HFS+ or Apple is planning to use APFS with case sensitive version of default file-system.
Default case sensitivity of APFS in pre installed Mac 10.13
My MacBook was installed (default choices for conversion) with case-insensitive APFS
From What’s New in APFS (WWDC Session 715) slide 56, Unicode and Normalization – macOS:
APFS
Case-insensitive and normalization-insensitive by default
Unicode 9.0
Forward compatible
Unassigned code points are not allowed
Hash based comparison
Canonical folding