From other sources I read:
Datuk Pahamin's group - The original AirAsia partner who was instrumental in Tony obtaining Tun M's blessing to start (his version of) AirAsia
Jentayu Danaraksa - Firm that tried to buy out MAS in 2014 from Khazanah, if you all may recall. One of their members include Shukor Yusof, former Standard & Poor's aviation analyst
Weststar Aviation - Mainly General Aviation and Helicopter charter service company. Partly owned by mega private equity firm KKR
Group backed by Qatari Investors - Most interesting out of the lot, but the most mysterious thus far. Rumored to already been active in the Malaysian aviation scene with shareholdings in major entities, but very discreetly.
Need to correct this a bit. The rumored four is excluding the Qatar group, who are instead BEHIND some of the groups.
The fourth group is led by ex-CEO of MAS Tan Sri Abdul Aziz Abdul Rahman.
Meanwhile, Weststar was sort of nominated by Khazanah, and will likely partner with Datuk Pahamin's group.
Surely QR don't need MH, considering they have IAG in their hands, which is far more profitable.
Maybe IAG will the be ultimate entity owning it? Jeng jeng jeng....