Let's see -
Since we have Starman now as Denny Blaine with the JSA, the Waid Thom Kallor will survive and any other Star Boys will bite it. Waid Saturn Girl, Lightning Lad, Ultra Boy, Light Lass, Karate Kid and Invisible Kid will survive as well. So...
Survivors are:
1) Star Boy (Waid)
2) Light Lass (Waid)
3) Saturn Girl (Waid)
4) Lightning Lad (Waid)
5) Ultra Boy (Waid)
6) Karate Kid (Waid)
7) Invisible Kid (Waid)
8) Brainiac 5 (Johns)
9) Sun Boy (Johns)
10) Gim and Yera (Johns)
Add Dawnstar (Johns), Wildfire (Johns), Blok (Johns), Timber Wolf (Johns), Dream Girl (Johns) and Sensor Girl (Johns) as survivors. Also, Violet, Phantom Girl, Shady, Element Lad, Triad, XS, Gear, ME-Lad, Bouncing Boy, White Witch, Ferro Lad, Quantum Kid, Kinetix, and Valor from the third group.
Fodder:
All the alternate versions of the above listed, including Cham for Yera. Yes, some forty-odd Legionnaires are gonna get blown away in THREE ISSUES. Who'd have thought the 50th anniversary of the Legion would be like this?