That's an excellent point.

Sadly, I don't think the average consumer knows or cares about the badness that is lossy-to-lossy transcoding.

For those who do, aptX support is pretty easy to find in the sense that vendors tend to make "aptX" searchable in the name and/or description. (If you Google "amazon aptx headphones", you'll see what I mean.)

Finally, this is a great example of how Apple gets to "own" the mindshare for tech they don't invent. If Apple decides to hang their hat on the aptX brand for the iPhone 7 launch, that'll be how most people hear about it for the first time. Since aptX isn't their brand, it's more likely that Apple will simply tout "perfect wireless audio" and make sure customers know to look for "Made for iPhone" headphones.