My initial reaction was positive, but now I think that creative space would be better used on a new character. A vampire champ who has some lifesteal components but also utilizes other aspects of the vampire fantasy, such as shape shifting, speed/teleporting, raw physical strength and even demonic traits.
I hesitate to add biting since that would go into Warwick's territory, especially considering how his tentative kit rework seems to emphasize the theme of teeth and claws even more than what he has now. Then again, if this theoretical vampire character had some sort of rivalry with Warwick, some kit similarities could work - as in the case of Rengar and Khazix, who both fill the niche of a stealthy ambush predator.