The new NIV has Isaiah 9 saying:
7 Of the greatness of his government and peace
there will be no end.
He will reign on David’s throne
and over his kingdom,
establishing and upholding it
with justice and righteousness
from that time on and forever.
This departs from the traditional translation: "of the increase of his government." Would I be right in guessing that King James' translators were more post-millenial than we tend to be??
To be fair 'greatness' does seem a more straightforward translation of the word. But the context of "no end" and "forever" makes 'increase' a more than acceptable translation too.
I just wonder whether the new NIV translators have been thrown by the murky ambiguity of Isaiah's words here. I mean, who, after all, can discern the referent here within the rich tapestry of rise and fall in the history of Israel's kings. After all wasn't Solomon also Wonderful Counsellor, Mighty God, Everlasting Father and Prince of Peace... (snark, snark, gripe, grumble).
The problem as I see it with 'greatness' is that it's too vague and doesn't carry over the idea of quantity that seems to be an aspect of the word (cf. Isaiah 23v33, Ezekiel 23v32; it's also related I think to the word for 'multiplied' in v2). 'Greatness' the way we use it can just mean 'it's really really good/ fun/ cool/ nice' without any reference to size.