Let's look back and examine what exactly happened after the Game Boy Advance was prematurely replaced in late 2004/early 2005.
These are Nintendo published releases on the GBA from January 2005 and on. The first category includes games that were already released in Japan prior to 2005.
Code:
[B]Late Western releases:[/B]
NES Classics Series: Dr. Mario, Metroid, and Zelda II (EU 2005)
The Legend of Zelda: The Minish Cap (NA 2005)
Yoshi's Universal Gravitation/Topsy-Turvy (NA + EU 2005)
Fire Emblem: The Sacred Stones (NA + EU, 2005)
WarioWare: Twisted (NA + EU, 2005)
Code:
[B]Late releases:[/B]
Mario Party Advance (2005)
Dynasty Warriors Advance (2005)
Donkey Kong Country 3 (2005, NA + EU only)
DK: King of Swing (2005)
Pokémon Emerald (2005)
Dr. Mario/Puzzle League (2005)
Mario Tennis: Power Tour (2005)
Pokémon Mystery Dungeon: Red Rescue Team
(2005-2006)
Code:
[B]Japan Only:[/B]
Sennen Kazoku (2005 JP only)
Nonono Puzzle Chalien (2005 JP only)
Bit Generations Series (2006 JP only, 7 individual budget titles)
Rhythm Heaven (2006 JP only)
Mother 3 (2006 JP only)
Eyeshield 21: Devilbats Devildays (2006 JP only)
The Tower SP (2006, Sega published in NA)
Calciobit (2006)
Code:
[B]Japan and North America only:[/B]
Drill Dozer (JP + NA, 2005-2006)
In the below the original Japanese date is disregarded as either Square Enix or Namco published the game in the region. Regardless, only Tales of Phantasia's Japanese GBA release predates 2005.
Code:
[B]Nintendo published third-party games outside Japan 2005-:[/B]
Final Fantasy IV Advance (2005)
Tales of Phantasia (2006)
Polarium Advance (2006)
Final Fantasy V Advance (2006)
Final Fantasy VI Advance (2007)
How did Nintendo not seriously treat the Game Boy Advance as a third pillar with all of this? Forgive and please correct me if I left out any titles or included any erroneous information. Generally though, the perception that Nintendo abandoned the GBA right away seems to be a myth.
Edit: I think that's all of them now.