I try to figure something out that is highly speculative but incorporates some things we heard about (just without the necessary details to understand how the system really looks like.)
Wizard prepares spells (possible less than today), say Magic Missile.
As long as he has Magic Missile prepared, he can fire a bolt of force as a ranged touch attack, dealing 1d6 + caster level points of damage per round.
He can also cast, once per encounter, a a Magic Missile dealing 1d6 points of damage per 2 caster levels that automatically hits.
And once per day, he can cast a Magic Missile that deals 1d6+caster level damage to 1 target per caster level, automatically hitting each target. (This use might remove the spells from his list of prepared spells, or make it impossible to use the spell again during this encounter.)
A Wizard prepares Mount (say, in his "utility silo" spell slot, if that how it works):
As long as he has it prepared, he can do the following things:
Summon a Heavy Warhorse or Warpony once per encounter that lasts for one minute, serving as his combat mount (or that of another character?)
Summon one Light Horse, Pony or Mule once per day, that lasts for two hours per level. (This use might or might not remove the spells from his list of prepared spells, or this use is exclusive with the other)
So you still have to decide: Which spell do I prepare? When do I use which benefit from the spell? When do I use the more powerful effect?)
This might not at all be how it will work, but it gives at least an example how using 1/encounter abilities can work in the great scheme without entirely removing resource management.
There is also a further alternative: Maybe spell casting times increase for some spells, which means that per day resource management ends up into per encounter resource management.