There's hope for a smooth transition at TVNZ as its shakes up the flagship 6pm news bulletin.

Presenter Simon Dallow's stepping down this month after almost two decades - to be replaced by weekend newsreader Melissa Stokes.

Media commentator Duncan Greive says TVNZ's made the safe choice, given it's not reaching a lot of new viewers.

"If you look at the ratings for ThreeNews, there's not a lot there, they've gone down a bit."

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