The US seems likely to leave the UPU or to force through major & rapid changes to the UPU that will greatly impact the global postal shipping system. There are plenty of articles about this in Google News but it hasn't received extensive mainstream coverage yet. This one is pretty good, IMO, but have a dig around in Google News (US leaving UPU or UPU meeting are likely good search terms) to see what comes up.

This move by the US is a double-edged sword. On one hand it will probably do a lot to stop the massive flood of ultra-cheap items being shipped individually from China. All that stuff you see on eBay for 99c with free shipping would stop pretty much immediately. That will create some demand and opportunity for domestic sellers in the US who are willing to wholesale batches of product from China for US resale.

On the other hand though anyone shipping out of the US after October 1st could face some major business disruption.

And businesses who are shipping to the US, even if that country does have a fair and balanced agreement with the USPS, prices are still going to go up both ways.

Likewise anyone who has a business that involves drop-shipping items from China is probably going to face a LOT of business disruption. Dropshippers in particular are going to get hit really hard.

This will likely have knock-on effects to people who are in other countries, even if you don’t deal with the US at all. Depending on how things unfold the entire UPU system could end up being renegotiated, or in a worst case scenario the treaty could fall apart.