If you forgot (or are hearing it for the first time), the Microsoft and Platinum collaboration Scalebound was canceled several months ago.
With regards to the Scalebound trademark, companies renew trademarks all the time, and in the case of Scalebound, it's still very fresh in gamer's minds as a title developed for and by Xbox.
The most likely explanation is that Microsoft is preventing others from using the Scalebound name, retaining ownership of the IP.
"After careful deliberation, Microsoft Studios has come to the decision to end production for Scalebound", is what Microsoft said of Platinum Games' ill-fated Scalebound back in January. And thanks to the internet, the news has spread like wildfire.
A trademark filing is of course far from proof that Microsoft is actively doing anything with the property. If it's not true, they could be planning any number of things with the IP. The noise around the game had largely died down, and most folks had accepted that it wasn't going to happen until today, when it came to light that Microsoft had renewed its trademark on the game's name. Either way, Platinum Games is not involved and we must take the idea of a "reboot" with a grain of salt.
The news appeared on SomosXbox, which found the trademark renewal on Justia Trademarks. I mean, some of us kind of saw it coming in a way given the Xbox One's terrible performance in Japan, but I was still hopeful that it would happen regardless.