This is a perfectly legitimate question. The VSL software has been discontinued and will not see further developments. It has been replaced by the "umbrella" driver, UC.
The main fix for your AudioBox that comes with UC is improved buffer modes. You can read more via the release notes for the driver:
https://pae-web.presonusmusic.com/downloads/products/release_notes/UC1.8_ReleaseNotes.pdf
As you've noticed, UC removes VSL functionality. You're welcome to uninstall UC and install the previous driver (AudioBox v1.3) if you'd like your VSL functionality back.
