The Magic Mouse has been around since 2009. And while it's moved from batteries to a rechargeable system and from Lighting to a USB-C port, it hasn't changed as drastically since it came out. Bloomberg's Mark Gurman reports in his Power On newsletter that Apple is prototyping versions of the mouse aimed at addressing the needs of the "modern era." And yes, that includes the often-complained charging port location.
However, we might have to wait between 12 and 18 months. Gurman reports it would take months or years of hardware engineering, software development, and operations work after the designers finalize its look.