POS will boost Ether to over 1000USD.
5% Reward is more than great for just holding Ether. This will be the future, near 0 electricity.
ETH Devs are basically famous for missing deadlines.
Back when ETH launched in late 2015, it was said that POS would launch sometime in Summer of 2016. And because of their promise, I've never upgraded to more efficient GPUs, which at the time were the AMD Nano/Fury's. And basically kept waiting and waiting for POS updates and from what I can tell its still a long ways away.
Another issue is that who knows how it will work in practise to compared to how they have it analyzed in theory. I hope that POS works out but like others have said before, it will make ETH centralized because there will be a small percentage of individuals who owns most of the coins.
What the muggles don't realize is how complex these things are. The sharding spec is certainly non-trivial. It's why there are literally a dozen or so different teams working on various implementations.
PoS isn't like throwing up some website code. It's unbroken ground. Even giving the date of 2016 - 2 years is not much time.