No this won’t happen. They actually were thinking of switching to an algo called ProgPOW a few years back to get ASICs off the network and last minute it was cancelled. It was cancelled because the ASICs aren’t a 51% attack risk so they moved on.
If there are going to be issues with ETH going fully POS they will just revert to the old mining algo, I don’t think they will change it so ASICs get booted off the network.
You think so? The rumour I'm hearing is Ethereum team are planning to get rid of Asic once and for all, they are just using the PoS switch to buy themselves some time, they won't see it coming, anyway this is still a rumour too.