As I understand it ...
Boeing kept quiet about MCAS because they wanted to present it as "the same as an NG", and didn't want to do any additional simulator training. Not so much because it would be an issue to allocate crews for this as the aircraft came on line, but because no simulators would be available in time. And apparently they are still not, only a couple are available now, and some of the major owners have still not yet got one. That's the real delay there would have been in introduction of the aircraft.
One has to ask, of the few simulators already around, did they have the fidelity to represent an AoA failure accurately.
Now we have the prospect of the aircraft being offered for recertification, but these training aids are still not fully available. And are they going to represent the antics of the New MCAS properly ? So while the aircraft may get recertified, whatever will be required to get the crews up to standard before they first start using it. We already have accounts of established NG crews being presented with a Max one day, in revenue service, after just the PowerPoint training, and feeling it was far more different than they had been given to understand.