If you are wondering what happened to Darth Malgus, this clip from the San Diego Cantina Tour may have some answers. Clip taken from @iamwillgriggs and @Heather_Pls.
Important Update. SWTOR Lead Writer Charles Boyd just commented on twitter the Malgus part was cut from the trailer and he may not be returning after all (fate uncertain).
— Charles Boyd (@Charles_Boyd) July 12, 2015
Video Clip taken from @iamwillgriggs
— Will Griggs (@iamwillgriggs) July 11, 2015
Concept Art taken from @Heather_Pls.