From what I have been reading is that they believe that the updated customs process will be based on enhancing the "CBP Entry Type 11" process for items valued less than $2500. I've read that what they are working on is; any country that has a tariff in place will be required to prepare paperwork (all online) that will clearly state the harmonized 10 digit code for the item and pay the associated fees and tariffs upfront* before the item/s off-load to pass through CBP. All of the Tariff required packages with pass through an updated informal type 11 process.
The De Minimis process will remain in place for all other countries of origin that do not have trade restrictions.
(One thing I read is that they are working to figure out how to restrict 2nd and 3rd country exporters from taking packages sent from Hong Kong and China and forwarding them to the US under the guise that the items originated in their country.) Stiff penalties if these countries are caught doing this and perhaps tariffs added to all of their exports.
* I laugh at this because the current administration will claim that China is paying for the Tariff, rather than the consumer, because the tariffs are being paid for ahead of time by the shipper/Seller. (In reality, the buyer will pay 20%+ or more upfront for the item they purchased from an Aliexpress store.)
Keep an eye on HR 7979, which is the legislation proposed and pending in the House that would require this proceedure.