Did you notice how during the final scene of the play, Cranmer gives a long—and we mean long—speech about how awesome baby Elizabeth will be one day? If you were scratching your head wondering what gives, let us fill you in: that baby ends up becoming Queen Elizabeth I, Shakespeare's queen. She was on the throne when he was writing a good number of his plays.
Even though Henry VIII was written after she died, Shakespeare still went out of his way to give his former queen some major props.
Now, Shakespeare was sort of obligated to promote the idea that the Tudors brought about a golden age in England. Not only that, but the official line was that Henry VIII's reign was divinely sanctioned, meaning that God supposedly wanted a Tudor on the throne.
So when Cranmer (a figure representing the Church) goes on and on about how Elizabeth will "be loved and feared" and "her foes shake like a field of beaten corn," that's Shakespeare's way of saying how that this baby will be mega. It's his way of glossing over the fact that Henry really wanted a boy and was bummed when his baby daughter came along.
But Shakespeare doesn't stop there. He also writes about how awesome the next monarch (James I, who was on the throne when Shakespeare wrote this play) will be, too. He talks about James as the one to "make new nations" and "reach his branches to all the plains about him."
Shakespeare's no dummy. He knows that this play is a good opportunity to say, hey, isn't our king fabulous? James was the patron (or, the money) of his company, after all.
But here's another question: do you think Shakespeare is 100% serious? In a way, the whole play kind of undermines its own second title, All is True. All of the political truths in this play are relative, so when someone goes off and praises a monarch, you should turn up your snark radar and make sure there isn't more to that praise than meets the eye. Shakespeare's not going to give us any easy answers; it seems like his main goal is to make us think.