If you're referring to this comment; "You can visit old planets too, and we have refreshed the visuals on them.".
That doesn't say that the visuals have been updated for Horizons; just old planets have been given a makeover for Odyssey, as far as I can tell.
Or did you mean something else?
Yep, that's how I read it too. All planets will be getting whatever 'new tech' is coming with Odyssey, but if you launch the game via Horizons then it will all be the same as it is now. (I mean, they're not likely to give half of the first new paid DLC in four years away for free.)
Honestly, the lack of clarity from FD over this subject is really bad (and to me at least suggests nothing positive).
1. At launch Odyssey and all the new content coming with it, visual / graphics updates and legs will not support VR, however we are working on VR support for Odyssey and expect to have support for flying and SRV driving within
timeframe (I mean it's still nearly a year away), and VR support for legs - if that is possible - by
timeframe.
2. Odyssey will not be getting VR support because we do not feel that it will work for legs, so all support for VR is being removed. However, planetary / visual upgrades will be applied in Horizons which still supports VR.
3. We're really proud of our support for VR since the game launched, one of the first AAA games to fully support the VR experience. Unfortunately, we are now dropping that support.
I'm sorry to say that I think number three is the most likely - because surely if it were either of the others someone from FD would have been happy to let the community know that by now...