Exhaustion as pointed out is loosely related D&D core mechanic there, does not indicate anything in regards to any potential rest system.
I'm inclinded to think Larian will figure something out at least for higher difficulties at launch. For Normal, though, would not be surprised to see it remaining as is with only limitation not resting near enemies - NWN/NWN2 did just that and somehow these games did not explode there. Heck old BG games were not restrictive there either, you had proximity and little else.
So Larian might just go same route of long rest being generally available plenty.
