Spoiler in After Credits of Episode 9

Dan says:

“You know, we've seen innie Mark and outie Mark walk around in each other's lives. We've seen them start to see glimpses of each other's lives. What we've never had between them is an actual conversation where the many, many complex feelings that they would have for each other are actually able to be talked through. So that's what we leave episode 9 with, is the promise of that long-awaited final meeting where they're actually going to speak to each other.”

So iMark and oMark are somehow gonna talk to each other in the season finale.