Details are sparse at the moment, but the retro revival is still strong. I grew up with a Genesis because SEGA DOES WHAT NINTENDON'T amirite? So I'm super excited about this, because unlike some of my other classic systems, my Genesis is a little flaky, and maybe this new mini-Genesis will come with some of the games I drooled over as a kid but never got to play.
It's important to note, however, that this hasn't been announced outside of Japan yet, so it's possible that we won't see it in the west, but that would be surprising.
Don't confuse this with the unofficial Sega Genesis Flashback. China's AtGames released this a couple years back, but it was not first-party and had no shortage of issues. Here's hoping the official version will be much better.
Via cnet: https://www.cnet.com/news/sega-megadrive-mini-announce/
Official announcement: https://youtu.be/bLHAMwGyDNE?t=51m