Hotline Miami 2: Wrong Number was initially slated for release as DLC for the original Hotline Miami, its developers revealed in a recent feature at VG247.
Dennaton notes that Hotline Miami 2 was conceived as an expansion, but was fleshed out into a full sequel as its scope grew during development. Hotline Miami 2 will feature multiple playable characters and factions, and its narrative will weave new elements throughout its predecessor's timeline.
Hotline Miami 2 is scheduled for release later this year, and will be the "grand finale" concluding chapter for the series.
Source: VG247