Neither M2 nor Konami has confirmed this mind you. However, a recent Australian rating certification listing does suggest that the said collection of Castlevania titles is coming soon.
When Is the Castlevania Advance Collection Coming?
Eagle-eyed fans recently spotted Australia's rating board giving the Castlevania Advance Collection an "M" rating for mature. This is the equivalent of a "Teen" rating or "PEGI 12" in other countries. The listing is dated June 18, 2021. This indicates that it is recent, and puts M2 as its author.
The Tokyo-based studio previously worked on the Castlevania Anniversary Collection and the Contra Anniversary Collection.
Although the Castlevania Advance Collection doesn't specifically list all the games that it will include, it doesn't take a rocket scientist to know which ones will be a part of the compilation.
In total, Konami released three Castlevania games for the Game Boy Advance: Harmony of Dissonance, Circle of the Moon, and Aria of Sorrow.
All the aforementioned Castlevania titles never made their way to other platforms outside of the Game Boy Advance and the Wii U (via Virtual Console). However, according to the listing, Castlevania Advance Collection is a "multi-platform" game. This suggests that Konami intends to release it on the Nintendo Switch, as well as other platforms. This would mark the first time that these games will be available on a non-Nintendo platform.
Either way, the listing does confirm that a Castlevania Advance Collection is in the works and coming. When exactly is the question now.
Listings have been a consistent source of information about upcoming video games. Most recently, ESRB and PEGI leaked The Medium for the PS5 and Godfall for the PS4, respectively. Both listings turned out to be true as the game's developers confirmed that the PS5 version of The Medium and the PS4 backport of Godfall was coming.
Releasing a collection of the Castlevania games for the Game Boy Advance is also in line with Konami's recent moves.
We can only hope that this also means that Konami is planning on working on some of its forgotten franchises.