> We've seen something like this before, when AIM allowed MSN Messenger to interoperate. I know this is a little different, but that was still how AIM lost.

Lost? AIM was the dominant IM platform in the US until the late 00s/early 10s when mobile and cloud-based services took over. First SMS/MMS and then platforms like Facebook Messenger, Google Hangouts, and Skype.

The only place MSN was dominant was third-world countries like Brazil.