$ cat >lol.txt
Y2K articles before year 2000:
"OMG, rogue Y2K is going to kill us all!"
Y2K articles after year 2000:
"Hahaha, remember how everyone was so scared of Y2K? ROFL!"
^D
$ sed 's/Y2K/AGI/' lol.txt | sed 's/2000/20XX/'

From Google Books Ngram viewer "y2k problem"
https://books.google.com/ngrams/graph?content=y2k+problem&year_start=1990&year_end=2019&corpus=en-2019&smoothing=3
-- Yann LeCun