It strikes me as about ten years too late, since Rocky IV came out 30 years ago, and if his kid was born right at that time he'd be over the hill for a boxer starting out. Maybe they deal with it in the script. Maybe Creed's kid was born of his frozen--- Oh, never mind.
Looking at the cast list, it appears Michael Buffer, the ring announcer who trademarked "Let's get ready to RUMMMMMBLLLLLEEEE!" will not be in this one, although he was in Rocky V and Rocky Balboa (a.k.a. Rocky VI).
This means that they cannot legally use the phrase "Let's Get Ready to Rumble!" in the movie. It's a pity; people seem to expect that in big extravaganzas, which is why Buffer has appeared as himself in everything from Harlem Nights to Phineas and Ferb.
We can't have the ring announcer just standing there saying nothing when the big climactic fight gets going. Of course, had they asked me, I could have suggested some substitute non-trademarked expressions, like:
|Let's get ready to CRUMBLE!|
|Let's get ready to RAMBLE!|
|Let's get ready to BUMBLE!|
|Let's get ready to RUBBLE!|
|Let's get ready to ROUBLE!|
|Let's get ready to RHOMBUS!|
|Let's get ready to RUMPOLE!|
|Let's get ready to ROOMBA!|
|Let's get ready to GUMBALL!|
|Let's get ready to RIMBAUD!|
Although maybe Creed would be better with Rimbaud in it. Or Barney Rubble.