It is called "Ground Branch" and requires fan funding on their Kickstarter page.
As a developer say, the main player versus player gamemode will be based on Infiltration's EAS principles, but also Terrorist Hunt, as known from the old Rainbow Six games, was confirmed.
Realism (proper weapon handling and movement) is a main focus.
Above all Beppo, the lead developer of Infiltration is associated with the project.
This is the next INF as we all waited for. If you want it, support them!