Will not happen:
1. Abir considers Kuhu as her bro ( Refer to August 21 episode).
2. Abir was texting Mishti during the promo. Why would he do that if he's standing outside Kuhu's door?
3. There's been a lot of indication of Abir and Mishti getting married. They've performed so many rituals together. They exchanged their haldi - Kunal and Kuhu didn't even do that.
3. There's the SBS video that someone shared in this thread that it clearly shows that Kunal and Kuhu got married.
4. Abir brings Mishti to the mandaap. Why would he marry her sister when the girl he loves is right there?
And finally, here's a few pictures that were shared today ( Credit the original uploader):
Mishti and Abir: Upcoming Pictures ( Credit to the uploader).