Will LR 5.7 be able to read raw files from the new Nikon D500 when it is released in March?.....Thanks
You will need either the release of Lightroom that comes out after the D500 release, or the equivalent version of the Adobe DNG Converter
Judging from history, both that new release of LR and the DNG converter probably won't be ready when the camera becomes available. If using raw files is vital to you, you might want to hold off buying the camera until it's supported. Otherwise, you could shoot raw + JPEG for a while and save the raws for later import.