Well there's a difference between being in an alliance and a joint venture.
http://onemileatatime.boardingarea.com/2017/10/12/interline-codeshare-alliances-joint-ventures/
"If a codeshare agreement is like dating, then a joint venture is like getting married. A joint venture agreement is a massive business decision that typically requires extensive government approval. When airlines form a joint venture they coordinate pricing and schedules, and have a revenue sharing agreement."
The thought I had was how will this affect the requirement for pilot jobs? If airlines in a joint venture can coordinate pricing and scheduling, they can reduce the number of flights.
If I'm not mistaken Qantas and Emirates entered into an agreement in 2012, which shifted a lot of flying to Emirates.
Look at all the green routes operated by Emirates:
https://www.qantas.com/travel/airlines/qantas-emirates/global/en