Undergound Dystopian Nicknames
I like the idea O.M. brought up about the high tech requiring literacy and intelligence, so I agree there would probably be continuity in spelling.
The dystopian part, though, made me think of possible underground or gang style nicknames becoming more prevalently used than modern given names. For example, Sting, Hax, Manx, Nyte, Pixie, etc., i.e. any word that describes their unique speciality or personality trait. It could also be something like comic book heros - Deadpool, Nightcrawler, The Beast, Cap (Captain America), Iron Man, etc.
Perhaps their given name is used in polite society / at work, but when in a more underground setting, their slang names might be used more.
Pidgin of Earthly Languages
Another thing that comes to mind in a dystopian setting is a developing a pidgin of existing languages and their slang, and that could carry over into nicknames. Shakti, Pun, Wu, might be attractive.
Pidgin of Human & Alien Languages
Also, if any alien cultures have been encountered, their language traits could be incorporated/assimilated into names.
I met a guy who said he had one time dealt with a modern group of ascetic monks. He said they all had renounced their possessions and previous identities, and to pay homage to their diety and observe IT as superceeding all individual egos, they all called each other "Dada", since in Sanskrit "da" means "give". My friend said when he pressed them about it, they said they didn't much care about names...the context of the situation indicated which Dada was being referred to. For example, he said one Dada liked to play golf, so if someone said "Dada is playing golf" then you knew who was being referred to. I can't honestly imagine how that worked out, except that perhaps their lives were pretty much interchangeable in terms of who needed to be reffered to--any one of them was good enough.
Another idea, similar to Shadow1024's, is perhaps each person could have a unique serial number, perhaps embedded in an RFID chip implant, or as a barcode tattoo. Perhaps, though, instead of calling each other by their full serial numbers, they just refer to each other by the least amount of last digits appropriate for the number of people in the environment. For example Jack, who's ID number was 5821247658, could be called "658" when lots of people (i.e. 999 or less) were present, "58" if there were only 99 or less around, and simply "8" if there were just a few people together.