Nobody (or nearly nobody) is doing or wants 384khz in studios. 192khz is next to non-existant as well and it gets pretty heated in the forums when people discuss whether there's any benefit to 192 over 96 and it usually comes down to "it's good if your equipment supports it because it will be more accurate at lower sample rates". Some tracking engineers will record at 88 or 96, but it's usually 48k. The tradeoff between disk space and sound quality for higher sample rates just isn't attractive. When you have 30, 40, or more tracks plus alternate takes plus renders plus bounced down tracks, all at several minutes long, that gets huge really fast and you can't just burn a CD with those files for backups anymore. Having a bunch of in-flight projects on the computer at the same time, you have to be mindful of disk space. The CPU use required to process that gets really big too, especially if you use a lot of plugins and a lot of tracks, and most plugins don't even support 192, never mind 384. Forget about tracking a lot of them at once, the latency can get pretty big. I have not seen software that advertised support for 384. Also in the mix is the fact that many of the ADC/DAC interfaces in common use don't even support a 192khz samplerate, and you'd possibly need more digital clocks. That gets expensive real fast. Now, I know some people would do it and I'd see massive threads in the engineering forums if it became an advertised feature! There would even be one or two people who would claim you can hear a difference, and a huge argument about that.
24-bit is fairly standard and 32-bit is in use by a lot of people who want that nearly infinite headroom while mixing.
It all gets downsampled to 44/16 (CD, MP3, AAC, YouTube) or 48/16-48/24 (Dolby Digital, DTS) for the end product anyway. We'll see what happens with the next gen stuff like Pono or whatever Apple is doing, if it goes the way of SACD and DVD-Audio.