We have the following that have been announced on the plate:
SiN 1.12, aka Original SiN. This is the original game in the original engine.
SiN Episodes. This is the Source-powered episodic release. While we have the major arc planned across multiple episodes, we only have Episode 1 in active production and Episode 2 in pre-production.
SiN: Source. This is the Source-port of original SiN, and is currently on hold while we finish SiN Episodes and SiN 1.12. Not sure when work on this will pick up.