I can't speak for the big guys, but I'm seeing more smaller Flash game devs make the transition from Flash to Haxe, mostly for the ease of porting to mobile/HTML5.
I've been making Flash games on and off since about 2007 and finally made the transition to Haxe with my latest game [1]. As others have commented, it's not perfect yet (i.e. some features aren't yet available on all targets), but I'll never be going back to Flash now.
2) Disney (using Flambe) -- web/mobile games
3) Flambe (Haxe game engine)
4) reach3DX (next-gen 3D engine by Gamebryo)
5) Defender's Quest 2 (me) (HaxeFlixel engine)
6) Even the Ocean (Anodyne devs) (HaxeFlixel engine)
7) Rymdkapsel (Grapefrukt games)
8) Cardinal Quest II -- web/mobile (HaxeFlixel engine)
9) TiVo -- interface stuff I guess?
10) Tizen
11) Firefox OS -- just partnered with Flambe
12) Stencyl (Haxe game engine)
13) Motion-Twin (game studio that created Haxe)
14) Shiro Games (EvoLand devs)
That's just off the top of my head. So anyone using HaxeFlixel/HaxePunk/reach3dx/Flambe/OpenFL/Stencyl are all using Haxe-based game engines.