Good luck finding treats that are not.
Demand will drive supply. Smart move on Petco's part...now if they'd restrict it to US/Canadian sources I'd trust it even more. Too much stuff gets shipped out of China and relabeled as coming from Vietnam, Cambodia, or other country in the area. It has already been a problem with fish, clothing, and other products, so I'd be pretty suspicious that pet treats made in China won't somehow find their way into the international supply chain.
That reminds me of a joke someone told me once. A co-worker from the Philippines told me her sister back home worked in a garment factory sewing "Made in USA" labels onto clothes made in China. And the running joke among employees was that only the labels were made in the US.
PetSmart has also announced they will also carry only Made in USA treats. there are websites which list treats made in the USA.
Petco has always had Made in the USA treats (at least mine has) but they're two or three times as expensive as the others.
I'd rather be thought of as absolutely ridiculous than as absolutely boring.
I've always fed my dogs food made in the USA too (Canidae). I remember when the whole scary gluten and melamine issues cropped up and there were pet deaths as a result, and being reassured by Canidae's information and philosophy.
It's a choice. You can find good human food too. It may take a little more effort and cost a little more, but that is the trade-off for having some comfort that you are not poisoning your pets or yourself.