FDev rarely invent something, then re-invent something else with a similar meaning. The Stellar Forge already assigns a thickness to the atmosphere type classification: they are "thin", "thick", or no adjective which is presumably equivalent to "normal". You can't see these classifications in-game but they're there in the journal files, so you can see them on EDSM. If Odyssey 1.0 is only getting "tenuous atmospheres", that probably equates to us just getting the atmospheres currently rated as "thin". On that basis, the only new world in
Sol system that would become landable in Odyssey is Pluto, with it's "thin methane" atmosphere.
All Earth-like atmospheres are rated "normal", no matter how thick or thin they actually are in terms of atmospheric pressure, so if this theory is true, we won't be getting any Earth-likes in the first iteration.