For a long time big miners have been threatening us with a hard fork. We tried to find ways to compromise in fear that they would act on their threat. However the more you comply when someone threatens you the more they will threaten you to get even more from you.
What's the best thing to do when you are under attack? Attack!
Those miners are big companies, they probably have investors, creditors, etc. it's not a single person who controls everything and can do whatever he wants. Let's say there is a credible threat that POW would be changed, would they be able to get more financing? Would the investors be happy? Would they put pressure on the CEO?
The original vision of Satoshi is that of a decentralized network and the number one threat Satoshi warned us about is the 51% attack. He never mentioned changing the POW but he also never mentioned not doing it. So clearly preventing a 51% attack and preserving decentralization would be a good reason to change POW according to Satoshi vision.
Do we need to change POW? It depends, we only need to do it if there is a credible threat of 51% attack or lack of decentralization.
How do we find out if there is such a threat? Very simple, if a miner is strong enough to threatens to make a hard fork then there is a lack of decentralization and a risk of 51% attack. If miners become less vocal and quickly implement segwit then there is no need to change POW.
If ASIC producers want to keep making money and keep the same POW they have to ensure themselves that the network stay decentralized. For example they could sell more of their ASIC instead of using it themselves. They have to understand that the network has a built-in protection in case of lack of decentralization which is changing the POW. It's in their best interest not to activate this built-in protection.
It's also in their best interest never to oppose publicly a technical improvement as this could indicate again a lack of decentralization and would require activating the built-in protection of changing POW.
POW can simply be changed every single time there is a strong signal that the network is not being decentralized. Do we need to do it now? Only if miners don't understand that if they don't want to be part of team bitcoin (decentralized) they will be fired.