You can have audio of arbitrary bitrate. Lossless just means it isn’t being resampled or transcoded in a way that prevents exactly reconstructing the original signal. There’s no reason why you couldn’t support lossless audio up to 700Kbps, and the difference between 700kbps and 1mbps is well outside the range of perceptibility. You can also losslessly compress most audio that humans listen to by a significant degree, which is a completely transparent way to support higher bitrates if you can spare the processing time.