I use 3.5" floppy disks as ice scrapers. 
I use them whenever I need to give someone a file in person, or otherwise can’t be bothered to e-mail them. The last one I used, I had to get some documents printed at staples, and I didn’t want to have them hold on to my USB stick.
Also, I occasionally burn mix CDs for my car, still.
I still have 5¼ (truly floppy) drives but haven’t used them in years. 
I use CDs for backup and in my car stereo. I also use them very rarely at work if some client wants documents in that format. I still use discs for video and games.
DVDs: We rent about one movie a week from Redbox. But it doesn’t stay on disc for long. I copy it to the server and watch it on our DVR. The disc goes back the same or next day. The file gets wiped right after we watch it. Online streaming isn’t quite there yet for our needs, but that’s going to happen at some point.
I don’t buy DVDs and I have tried to subtly make it clear that I don’t want any as gifts.
Music CDs: I have an CD/MP3 player in my car. So I load up a disc with a bunch of songs and listen to that for a long time. But even a CD of MP3s isn’t enough. So I’m going to go to “mechless” player soon. Fill a 32GB SD card with music and go that way. Mrs. FtG still has a regular CD player in her car. I’ll swap it out with my old one and start putting her music on MP3 CDs.
Data Discs: Pretty much done with this. For backups I use multiple HDs. A DVD isn’t really useful for me.
(Speaking of floppies: I upgraded my MB last year. It didn’t have a floppy connector. So I pulled the floppy drive out. It was unconnected most of the time anyway. Went thru some old floppy boxes and copied some memorabilia off. The floppy drive was a classic: it was an early upgrade to my old XT clone. ~20 years of service.)
I don’t see any point for me to get into BluRay. No more optical media in the future for me.
I keep looking at my 16GB microSD card. Smaller than my thumbnail. In year or two we’ll have 100-200GB cards. So much capacity. So easy to lose.
I back up my .avi, .divx, and .mlv media to dual layer (8.5GB) dvds - at least the stuff that I think I may want to go back to.
Still stick .mp3s on CD-R for use in the car stereo. (And backup.)
People have been predicting the death of optical discs for some time, but I understand that Fuji is expecting to get a disc to market by 2015 which fits 500GB per side and will be more cost-effective than blu-rays to manufacture, so I expect that the lifetime of optical discs will be extended somewhat. (Detail on that here.)
4K and 8K Ultra-HD sets/projectors haven’t begun to trickle down to the consumer electronic market yet, but it won’t be too long before they do. On that happy day when I can purchase movies at 7680 × 4320 resolution, I expect they’ll be delivered on optical discs of some description. (I sure as shinola won’t want to download/stream files of that size, or compromise on quality.)
Probably this one - Holographic Versatile Disc - Wikipedia
For file transfer I’ll use the Internet (Dropbox usually), unless there’s a ton of them in which case we’ll swap a hard drive.
I will still occasionally backup onto disc, though now that I think about it I haven’t actually done that in over a year.
For movies I still buy discs, we don’t really have any streaming movie services here in Oz, I don’t think. Our Internet is still limited by severe download quotas, so streaming with wild abandon is not a popular option.