Thanks to P5YCH0 for pointing this out.
Excerpt from GBA-News.com's exclusive news:
"Just as I was paying, the salesman looked at the worm-light with a little smile. Almost nostalgic, he said : "Hum... a worm-light ! And to think that in a few months it would be totally useless. It would only be Nintendo that would release a console with a lifetime of six months !".
Seems that the "GameBoy Advance 2" (as it will be called) has been in "preparation" for about 3 or 4 months, and it will be released in December in Japan.
News source: GBA-News.com