It is welcome news for the Wales skills coach after the recently announced summer departures of Gethin Jenkins, Huw Bennett, Luke Charteris and Aled Brew to France.
They will join former Ospreys trio Mike Phillips, Lee Byrne and James Hook across the Channel while Cardiff Blues also confirmed Rhys Thomas will leave for Wasps.
But Davies followed the example of Ospreys prop Adam Jones by putting pen to paper on a new two-year deal to end speculation about his future with Northampton Saints reportedly interested, and Jenkins believes it can only benefit the national side.
"It's always good to keep your best players in Wales, so it's nice to see Jon has signed for the Scarlets again," Jenkins told WalesOnline. "Jon is a hugely talented player who's playing exceptionally well and he's a key member of this Welsh side.
"Warren Gatland has always said he likes his best players playing in Wales if possible, and that's no different now. But it's not easy when players decide to go and play elsewhere.
"I don't always blame them. They have a living to make and a career to keep pursuing. If that means that they go across the water to France and play, then we have to back them to that degree as well.
"But we want our best players to stay here for as long as possible. It is important to have them for the full preparations leading up to these games."
However, while Jenkins is sad to see Davies' international teammates leave he believes opportunities could be created for the next generation of Welsh stars.
"There's a lot of young talent coming through and a lot have come through to play for Wales already. If that keeps happening we have a chance.
"It is important we keep bringing the youngsters through and maybe they can take some of the positions these guys are vacating at the regions."
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