My theory: Remember how Alucard drained the blood of the bosses and stole their abilities in MoF? I think:
1. Alucard impales Dracul with his "special sword," which I also say is the blade that Gabriel threw back at Pan, killing him, in LOS1.... mounted on the stake of the original Combat Cross.
2. While Dracul's impaled ane unable to move, Alucard bites Dracul and drains his blood...stealing his power, and even returns to how he looked when he was Trevor.
We'll see sooner than later.