This thread is going with the assumption that you actually like Vancian magic and want to see things like the 8 schools of magic return and do not care about things like wish spells.
Put simply what power level/balance do you want to see D&DN magic to have. These days the kids seem to like balance more and they do not like Spelldancers to have the ability to dance up infinite ability scores with a simple build that makes Pun Pun look silly.
I like ye olde classic wizards and priests etc mostly because thats what D&D has always had. I do not want spellcasting classes to be that drastically different from those I picked up twenty odd years ago. I do not care if they add other options to the game such as Warlocks, Sorcerers etc but I have certain expectations about what spellcasters can and can't do so no healing spells for wizards for example. A white mage class or prestige class that is arcane and heal I do not care about.
Anyway feel free to disagree here but 3rd ed was kind of broken in terms of magic due to the changeover from AD&D to 3rd ed. Put simply they buffed the spellcasters and nerfed the fighter (they did buff the thief/rogue though). This lead to things like CoDzilla which AD&D lacked although to be far wizards were the most powerful class there at higher level but they progressed slower and thieves and paladins were probably the weak classes. In terms of spellcaster power I would rate the classic D&D editions like this.
3.0 (haste, timestop, CodZilla in splats, Spelldancer, Incantrix, Red Wizard, Shadow Adept)
3.0 was the big offender in 3rd ed, 3.5 actually nerfed spellcasters and Pathfinder nerfed them again. Personally I did not mind the nerfs as something needed to be done about the spellcasters in 3.5. Anyway what power level do you expect/want from vancian magic? I kind of like the D&DN concentration mechanic which kind of limits the amount of spells one can stack which I am fine with. Improved Invisibility +Fly is a very old AD&D spell combo for example that was easy to recycle in 3rd ed as well.
Some spells should have some amount of DM arbitration built in such as wish. I "wish for a castle" could have results anywhere from getting a castle to having a castle appear above you and falling on you for 100d6 or more damage. That has always been one of the charms IMHO of the wish spell.
So where do you want the power level of magic to be and how important is balance to the grogs? Do people want 3.0 spell power or BECM levels of magic? If they made Pathfinder 2 or AD&D 3rd ed what would you want from vancian magic? Should they send Clerics and Druids back to level 7 magic as they are gish classes and that was one of the trade offs they used to have for better weapons, armor and combat ability? If you do not like vancian magic please feel free to start your own thread.
Fear is the Mind Killer