The only options I can think of are increasIng the number of letters and redefining “T” to “tetra” or even “thirty”.
Time to get started on a new RFC
https://wiki.c2.com/?ExtendedThreeLetterAcronym
Although I'd like to see something like XTLAs, for eXtensible Three Letter Acronyms.
Four letter acronym, experimental.
The only options I can think of are increasIng the number of letters and redefining “T” to “tetra” or even “thirty”.
Time to get started on a new RFC