If this was the junk product, it wouldn't go to the market and last this long.
Let's make sure we understand the meaning first. As I understand (and it took a second reading):
If this were really such a piece of junk as you say, then it would not have lasted on the open market for this long.
If this product was a piece of junk, it wouldn't have lasted this long on the open market.
What don't you understand about the changes?