I have Beeper. It works well, except that it doesn't support registering your phone number without an iPhone, so you can only use iMessage with an email address. I believe they are working on fixing that now.
How could they work on fixing that? iMessage currently requires a cell phone to activate a number on the iMessage network. Are you saying they're partnering with Apple to change this? Are they going to sim clone your number?
The entire integration with iMessage is reverse engineered. They need to reverse engineer the phone number registration part to get it working on Android phones.