from an Explorer point of view?
The galaxy is incommensurably big as it is now. It will become infinitely bigger with Odyssey and i'm not entirely sure it will be a good thing.
I don't think Odyssey will be a problem in that regard. Let's be honest here, exploration at the moment is very shallow in terms of gameplay.
Let's dissect it :
1) Navigation : mostly a non existant in terms of gameplay. Select a star, plot route. Done. The only times navigation ever becomes a challenge is
when exploring the rim or far above/below the galactic plane. There is no "terrain" in terms of witchspace, all the stars are maximally connected which means that
the only term driving the difficulty is the ratio of your FSD range to the local star density.
2) Exploring systems : a lot of time in FSS and then in depth exploration of a few objects. (In my case).
3) Looking at pretty things and taking picture with ASP in front of it
I have been exploring the Kepler Crest for a while now, and I must say that only 10% of my time exploring requires "skilled" input. The 90% of time is spent
in loading screens, scooping and FSS.
If Odyssey brings that to say 25%-75% by giving me more reasons to spend time to go in depth on a particular planet, it would be great news IMO.
Exploration is still pretty lacking IMO. Sure, there are amazing vistas to be found, but those are few and far between. At it's core, the exploration gameplay loop is the same as Lottery Scratch Tickets and Raffle. You play many times for naught, but sometimes you get something great.
TL

R if Odyssey pushes us to spend more time to skillfully explore sites in depth, it would improve exploration simply by decreasing the large low skill part of it (Jump-Honk-Scoop-FSS).