There have been many who have thought that the lack of development on Autodesk Design Review over the past few annual release cycles was a sign that Autodesk would soon retire the free product.
Even though AutoCAD has received new enhancements and features between the 2013 and 2018 releases, Design Review remained at the 2013 release. I don't know the reasoning behind this, but I surmise it may have to do with the fact that though Autodesk released a new AutoCAD product version every year, the AutoCAD DWG format had not changed between 2013 and 2017. This meant that no matter what AutoCAD software version you were running between 2013 and 2017, all of these files were compatible with each other because the DWG file format was still 2013-based. The 2018 release of AutoCAD saw the first DWG file format update in recent years, and so, logic would dictate that it was necessary to update Design Review to support AutoCAD's new format as well.
Design Review 2018 is virtually the same as the 2013 release, except for the official support for Windows 10, and cloud-based links to A360, A360 Viewer and BIM360 Docs.
Design Review may not be quite dead yet, but it's pretty much lived it's lifespan, looks like it's dead, and has all but been heaped upon the "Dead Cart".