[Milhouse]

Does this mean that there won't be support (in the future?) for USB /storage configurations?

No.

It just means that when a USB drive is being used for /Storage, it won't be possible to detect a broken SD or USB file system as the USB drive mounts too late leading resulting in fsck failure (because the drive is missing, so fsck bails before any file system is checked for errors). Consequently, forced fsck is impossible, due to the USB drive failure.

However, if you're using only the SD card for System and Storage then there will be no error and whenever a broken file system is detected, the forced fsck can be run.

See here for more details.