Well, the thing I want to see isn't really around in 5e either: a proper swordmage.
There is the magus, but that's not what I want. The magus is a class that sometimes hits things with swords, and sometimes casts spells. I want something like the 4e swordmage, which integrates magic and melee (and occasionally ranged, but I'd be comfortable keeping it to very short-range things other than things intended to reduce range). Like stabbing someone and sending a bolt of electricity through your weapon to stun them, or hammering the ground to set off a shockwave dealing damage in a cone, or teleporting behind someone and stabbing them in the back.