Apple can just pull this off Google Play and then also reject BB Messenger from iTunes App Store. Boom. Victory through lawyering with no technical work whatsoever. Two competitors down.
How could Apple convince Google to pull this from the Play Store?
C&D because of trademark infringement.
Assuming Apple doesn't kill it of course... There are some good reasons why Apple shouldn't kill it (network effect work both ways) but who knows what they will do.