This is the most important part. Immediately after filing, they’d have to start work against Sony and every other company that makes proprietary products. Which is why I don’t think it’s coming. They’re working, to be sure, but it’s a fine line to file anything that doesn’t put a target on the back of almost every other company that makes anything proprietary (including Tile).
The main reason why nothing has come forward in the US up to this point is that the adults eventually enter the room, realize how far reaching such a filing would be, and kill the effort.
The anti-trust investigation, which is necessary, is looking into what actions Apple has taken, either public or clandestinely, to force Apple’s hardware to have the sales it does. For example, illegal deals for software to be available exclusively on Apple platforms, purchasing competing handset makers then shuttering them, cutting deals with carriers so that they only carry the iPhone, etc.