Why Ethereum still not upgrade to POS. We have been waiting for so long time
Because making changes that are as huge as switching your algo takes much time. You couldn't honestly expect an overnight change and you would be surprised by the time they have already spent and the time it will still take to roll out. I would say give it until Q3-Q4 for the roll out, but even then don't hold your breathe.
Has it been set in stone that Ethereum goes full POS? Isn't there still the possibility that they will go with a hybrid system or has that been ruled out?