All the airlines participating in Global Explorer are possible additions
Global Explorer enables you to fly with selected airlines outside the oneworldŽ alliance, including Aer Lingus, Alaska Airlines and its affiliate Horizon Air, Bangkok Airways, Fiji Airways, Jetstar, Jetstar Asia, Jetstar Japan, Jetstar Pacific, Meridiana and WestJet; plus, Qantas code-share flights operated by Air Tahiti Nui.
On Air Italy (Meridiana) I think Qatar CEO said he wanted it to become a full member.
I'd also think Vueling and Level (both IAG owned) are likely additions.