In a game I'm playing (and I'm not telling the player off - it's a fair tactic as long as the game allows it), unescorted landing craft did just that - while loaded aircraft carriers, cruisers & destroyers in the target hex did nothing.
Had I known the capability existed to do so I might have garrisoned the city - or possibly not thinking it was to outlandish to ever happen
! lolAnd of course there remains the option of landing in an adjacent hex & moving in...
But generally IMO air and naval should relocate to somewhere within their movement range if possible, rather than be destroyed by land advancing.
Of course they should take a big hit in readiness for doing such an emergency evac, and/or lose some proportion of their force due to being unable to be moved - probably something like only the % ready have the opportunity to get away.


