Similar merger happened in Bangladesh in 2016. Axiata Group owns 68.3% share, while Bharti Group owns 25% in the merged entity Robi Axiata in Bangladesh.
In Sri Lanka, the Hutch - Etisalat merger happened in a similar way where Etisalat owns 15% of the survived entity, Hutch Sri Lanka.
This is actually beneficial to Airtel users, because you will get access to Dialog's largest coverage. On the other end, there is a possibility that Dialog may discontinue some of the prepaid plans of Airtel, but I assume postpaid plans will remain.
So, Dialog will now own 077, 076, 075 & 074. I wonder how TRCSL and Mobitel will react to this. The only thing I will miss is the Airtel's mobile app. It was a good one compared to the dog shit, MyDialog.