A Sonar OS X Alpha thread is
still pinned in the Sonar forum ,see :
http://forum.cakewalk.com/Lifetime-Updates-and-SONAR-OS-X-Alpha-m3429473.aspx So it´s not complete removed from Cakewalk webside.
This and several hinds of the cakewalk team in the forum
(the last I noticed in dec 16 )
that big things are in development and are short before a release
confirm imo that it´s not much time til an alpha release.
I think that it is not good that the bakers are announcing an alpha release
for the fall and still no post about the actual development state in the end of the wintertime.
This gives to much space for speculations.