Good News everyone! Looks like Sega has decided to go with M2, so emulation won't likely be a problem with this one. Also, it will use the 3 button layout, unless you go with the Japanese version. So far only 10 out of 40 games have been revealed, which includes:
Altered Beast
Castlevania: Bloodlines
Comix Zone
Dr. Robotnik’s Mean Bean Machine
Ecco the Dolphin
Gunstar Heroes
Shining Force
Sonic The Hedgehog
Space Harrier II
ToeJam & Earl
https://iearths.blogspot.com/2019/03/the-sega-genesis-mini-comes-home-this.html