This conversation has no sense since they are changing everything in the PTR now. I highly doubt that everything will remain the same (especially these bonus things, remember that they swapped the 2pc and 4pc for NH 2 or 1 week before the release).
But to answer to your question, I think that it will always be a good idea to load 30%haste 20%crit, and then going mastery. That's what I'm testing currently but the results are... ahem, no very "concluding". But yes, if 4th bonus remains the same, I think that mastery will be the way to go after reaching soft caps for haste an crit.