Manaless? Check
Free stats always-up offense to defense passive? Check
Breaks spellvamp itemization just by existing? Check
Targetted, low cooldown nuke? Check
Manaless isn't exactly an advantage when you spend your HP to cast things. Like, there's a significant downside to that. Killing yourself to cast things over using an alt resource that doesn't kill yourself? Not ideal.
Also - everything you listed there would still be something Vlad does post-rework.
Riot doesn't delete a champion and replace them with an entirely different character with a rework. They try to make the champion feel like the same champion, just with a funner and more balanced kit.
I mean - Karma was probably the most radical shift, but 3 of her 4 active abilities essentially stayed the same, and her aggressive mage/support archetype still stayed in tact.
Vladimir is a health-cost champion.
He is one of the rare champions that uses a joint defense/range pairing to survive long enough to do his job (rather than using defense(fighter/tank), defense+mobility(fighter/assassin), mobility(assassin), mobility+range(marksman), or range(mage))
He is heavily reliant on spell vamp what with being a spell-casting vampire.
And Vlad being manaless and reliant on sustain form damage dealt sets him up for playing in a sudo auto-attack fashion where he deals sustained damage.
Riot's reworks can't really do much in changing who a champion is, just tweak how there abilities really happen. And with Vlad getting reworked? All your issues with him would likely still remain through a rework.