Good funding for gen4 seems to be crucial - competition is announcing new solutions (though, rests to see if realistic). Time-frame for really successful gen4 deployment seems to shorten.
AM sold enough chips in less than a month in April to pay for gen 4 but used the money to fund the 60 Ph/s worth of gen 3 chips as gen 4 wasn't ready then. Given the months of chip sales, Tube sales and self-mining since then, AM likely acquired enough funding for gen 4 long ago. They just have to make sure it's free of major problems and get it out the door as soon as possible.
Let's hope, performance is going to be at least as planned.