How is resting, memorizing, finishing the casting and then forgetting (which is what happened in 1,2 and 3) different than fire and forget? It's not.
A 3.X Wizard does not "memorize" or "forget" spells. They start casting them, with the aid of the spell book, during an hour preparation time, leaving a final trigger step for later.
I also don't care for at-will either. I'll accept it, but it's not ideal.
Vancian style magic involves resource management. If you can just re-memorize spells and / or change them mid-day after a 5 minute break, it would seem you are simply trying to re-fluff the failed 4e magic system of encounter powers.
And having some spells with 5-minute rest times, and some (most, even) with 6 hour rest times still involves resource management. Lots of it. Even those short-prep spells are a significant resource to manage. It's a little different, sure. But if that's the extent of your argument, that it's different, so it's bad, then I guess there's nothing more to discuss.
And as far as I'm concerned, pure-Daily Vancian is a failed system... so let's table talk of which things are failures and which are not.
Tweaks, such as fewer spell slots isn't fundementally changing how Vancian magic works. That is like claiming a wizard with a 16 intelligence is somehow different than one who has more spell slots because he has an 18 int. # of spells has never been a hallmark of the Vancian style. The number of spells a wizard could have at one time has changed in every edition. That is a terrible argument.
The numbers have changed, sure, but the scaling rate has always been roughly the same. Without really changing that rate, dozens of spells at high level is pretty much inevitable. Suppose 5E's spell progression includes spell slots of a certain level being lost, as new spell levels are gained, so that more powerful spells are gained at some levels, but necessarily more spell slots. It has never worked that way in the past (except sort of in 4E). Would that still be Vancian-style?
It also doesn't change Rest, Memorize, Cast, Forget.
My suggestion tweaks the specific numbers for Rest, for a small subset of spells.
3.X completely killed Memorize and Forget, and replaced them with something else.
What "Cast" means changed fundamentally, from 1E/2E (where casting times longer than melee attacks were the norm, and easy to interrupt) to 3.X where most cast in a single action, same as an attack, and a spell was nearly impossible to interrupt.
But yeah, the thing that looks kind of like 4E. Can't have that.