It will be supercruising into the atmosphere... what else?
I'd rather have that than a velocity boost in atmospheres for conventional drives (if anything it should be lowered because of friction). How else are atmospheric battles realizeable? It will likely be a form of "atmospheric supercruising" below velocities of 30 km/s that comes with the gear required for planetary landings (something like an "atmospheric module" for the FSD). I don't have a problem with that, but i would have a big, big problem with absurd solutions that break with the established logic of the game mechanics.
Supercruising in atmospheres could be linked to all kinds of problems, like severe turbulents that require dexterity and good reflexes from the player, especially from whale pilots, acidic rain that requires a shield, flying creatures smashed against the hull/shield (blood & guts on canopy?), and other such masochistic pleasures.
And of course we won't be able to land everywhere or fly over cities with futuristic skyscrapers and arcologies and pulsating city live, there will be spots we can lock on when supercruising and approach after disengaging FSD, akin to supercruising to stations. However i think it's possible to create seamlessly accessible surfaces on planets (at least for surface vehicles, or feet) without atmospheres and without large structures, that would already be awesome.
This. I can't see how it's going to work without time compression, a feature that is now impossible to implement as it's a multiplayer game.