I would take out about half of it.

I would let the CP changes happen but not then shred all the class sustain abilities or mess with the abilities at all.

I would keep some of the changes to the stronger sustain passives, abilities and gear. I'd nerf Worms, and Vigor and probably the redgaurd passive and others that are strong and commonly used.

I feel like their justification for these patch notes is sound but thier basic dismantling a key pieces of thier own game like this is just too much at once.

Slow down sllloow down, too much change at once and a lot of that to stuff for which it is honestly not needed. If you slowly made these changes it is like a lobster in hot water people would not really notice, they would have time to adapt and never really feel the sustain disappearing, or rather they will just reach a point when they realise they need more sustain and go work on that.

Also why you no nerf sorc?