I may be missing something; I'm jumping at the bits to use something like this, and I'm quite the opposite of spammer - I'm just a nerd with heterogeneous family and friends who refuse to all magically switch to my recommended and obviously superior chat app :P
that's my point. for every one ultra power user who will have a dedicated root IOS device just to bridge all that, there will be thousands of spammers doing it for a profit.
The only solution to IM fragmentation is decent interoperable clients. But looking at the past, that is the way to kill the ecosystem too.
No user will ever use this in the way you are advertising here.