it would require a pretty comprehensive rework, yes. You'd need to (as an example):

• give martials something really cool that they can do to compete with the "cool factor" spells offer (I think having a large variety of weapon options would help, especially if the weapons all feel different and have different mechanical effects)

• Let martials use their physical prowess to dynamically interact with the battle (They can already do things like shoving enemies, but a really robust list of tricks that characters can do with their athletics, acrobatics, stealth, medicine, etc. skills could really help level the playing field. After all, spells are mostly useful for their utility and not just raw damage.)

• Make spells less all-or-nothing using multiple saving throws or varying levels of success (this lets you nerf the "top end" of spells while keeping their overall power the same)

• give martials more ways to cheat the action economy, like more actions per turn on average than casters get

• make more enemies resist magic but weak to normal weapons, or make more enemies weak to certain kinds of physical damage (slashing, piercing, silver, etc.)

• give martial characters "backdoors" into magical skill (for example, maybe characters with a high arcana skill can do magic as long as they have time to prepare - like rituals instead of combat magic - or they could use arcana and a satchel full of scrolls/wands to cast magic even as a martial)

• give characters more access to ability score increases on their weaker ability scores so they don't have to optimize as heavily around only one ability score

... just to name a few I'd have in mind