Because pretty much across the board, the instances of "The Wolverine treatment" we've seen have been to try and make their character line-up more diverse (Sam Wilson as the new Captain America, Laura Kinney as the new Wolverine, Amadeus Cho as the new Hulk, and so on). Making Else Bloodstone the new Blade would have done the exact opposite, so I'm sure the people at Marvel are aware that such a move would have gone over like a lead balloon.