Why has nobody left yet?
It is all economics. And yes in todays situation there is no need for a base yet since there is not a shortage of pilots anymore, EK and EY take no DEC at the moment and even QR seemed to be very successful recruiting in the USA. But times will change, with all the aircraft ordered there will be a shortage soon and it will be massive.
I still think that there would be a possibility to hire contract pilots with base in US or AUS. Also with a clever roster you could right now schedule 2 week on and 2 weeks off and still fly 85 hours, so the pilots and their families could live at home in Europe or India or wherever. Of course then there might be a big tax issue depending on the home country. But this would be the problem of the individual pilot not of the company.