Apparently, it was sold to "Tymshare" in 1977, but what happened to it after that? Who has the software now? Could it ever be emulated?
Yes, it was sold to Tymshare. The project continued under the name Augment, running on a modified TENEX, called August, on a KA10 computer. It was later ported to TOPS-20 on a KL10. Tymshare also made an "Augment Engine" based on a Foonly PDP-10 compatible computer. I believe it was last running on the KLH10 emulator. There was a project to revive this - https://www.softwarepreservation.org/projects/nlsproject/ and http://chm.cim3.net/wiki/NLS_Restoration.html - but it is rumored to have stalled due to unresolved IP rights.