last time i checked Drake could change into whoever he wanted, he even switched into looking like Blade. Notice when they brought Drake(looking like Blade) to the morgue to do a autopsy on his body, right when they started he switched into his regular Caucasian male and the doctors and nurses was scared and looked at each other then the movie ended. in the extra part of the movie it shows Drake( looking like Blade) getting up and killing the doctors.
Also at the end of the theatric movie it shows Drake( looking like Blade) with his shirt off, Blade had his shirt ON when he passed out, while Drake and Blade was fighting Drake was the 1 that has his shirt off. Ryan and the other girl came and took Blade away and left Drake laying there so he could give them time so they would have time to escape (and think they had Blades body which they didn't they had Dracula, to bad for them hehe) . Blade is sleeping, yes someday he will awake but that was Dracula not Blade.
Watch the movie again this way, they don't come out and say its Drake you have to use your head to understand whats going on. 🙂