I've found that once you have enough rapport with a company (usually 2 stars), they'll talk to you about their new product before they actually release it. They give you just enough lead time to order more and get it delivered before the factory stoppage happens.
For those companies where you don't have enough rapport, and therefore no advance warning, you can check the Trends report (Store --> Trends), to see which company is trending upwards. The ones to especially look out for are those that previously weren't on the top 5 list. You can make an educated guess from here.
eg. I get a message saying an unknown company is going to be releasing something new. I check the trends screen, and T.G. Trousers was not on the top 5 previously, and I don't have enough rapport for them to warn me. Grade One Garments is also trending upwards, but I do have enough rapport with them, and I didn't get any warning from them. So I can eliminate them, and make a guess that T.G. Trousers is the one I want.