Probably they will be the only sellers for these items, so no counterfeit problem there. I doubt this will fix the situation for other items.
Personally I've switched away from amazon, after twice in a row getting a box with a switched item (HDD and SSD, respectively, both replaced with smaller and cheaper versions, and both "Sold by and shipped from Amazon"). Amazon support was good, they replaced the product, but it's a hassle to have to return-ship and wait. Now I either buy off aliexpress (if I'm okay with cheap/counterfeit, which is fine for many items) or local stores (if it's a product where I really care about quality).
Personally I've switched away from amazon, after twice in a row getting a box with a switched item (HDD and SSD, respectively, both replaced with smaller and cheaper versions, and both "Sold by and shipped from Amazon"). Amazon support was good, they replaced the product, but it's a hassle to have to return-ship and wait. Now I either buy off aliexpress (if I'm okay with cheap/counterfeit, which is fine for many items) or local stores (if it's a product where I really care about quality).