The way that its worded, if the creature gets destroyed, bounced, exiled, or otherwise leaves the battlefield with the trigger on the stack, you get the Servos no matter what
Brawl Not Legal Vintage Legal Timeless Not Legal Commander Legal Pauper Legal Oathbreaker Legal Penny Legal Toolbox Buy This Card Notes and Rules Information for Return from Extinction: If you choose the second mode, the cards must share at least one creature type, such as Sliver or Warrior
If not, Serene Sleuth is a forgettable 2/2 that replaces itself
That includes the Gift Bundle, Booster Bundle, Scene Box, and Prerelease Pack
Grey Merchant of Asphodel was a real boost to Necropotence as it is a powerful effect regardless of the lifegain and has good devotion synergy with Necro
Gavin Verhey himself noted on the first look stream that If you transform this, you are not going to lose. This isnt particularly surprising