I don't think this necessarily confirms a Hitman 3 is in development quite yet - more so that IO is at the very least expecting they'll make it.
Here's the quote from the video:
"Earlier this year IO Interactive opened up a new studio across the bridge in Malmo, Sweden. And while much of the team is working on new Hitman content, and looking ahead to the third Hitman game, one that Hakan says may once-again go episodic, the majority of the studio at least here in Copenhagen is working on something secret, and rather excitingly, something new."
That timestamp I gave was actually incorrect. A lit bit earlier the Studio Head himself talked extensively about Hitman 3 and what it's going to be.
Also, Hitman 2 was made with half the team of the first game in 1 year and 9 months. Absolutely amazing.