After the halving, many ASIC models will either become unprofitable or give very little profit. And in order for large companies to use all the power for maximum profit, they will turn off thousands of old ASIC models.
And what will happen to these ASICs next?
Will they be sold to other countries or disposed of?
If you want to buy a used ASIC now, don't do it. After halving there will be a big discount on such ASICs on the market.
After the halving, a bunch of old ASICs are gonna hit the market cheap. Some miners with low electric bills will snap them up but a lot will just get junked. if you're looking to buy, hang tight, it'll be worth the wait.