I'm not saying they are going 12-0 until they get to the finals, but they finally seem to have it mostly figured out. And if they play at the level they can play at no one in the east is better. I think mostly this level of play will continue.
The Bucks will win a few games cause they are too good to not do so, but I see this series firmly being in the Celtics hands at this point point. The Bucks will play an amazing game and win that one, then steal a close one when the Celtics get cold at the wrong time, but that's all I think they can do if the Celtics play like they have been the last 5 games.
As for next series the Raptors are very good, but the Celtics just have so much depth and Irving will mostly cancel out Leonard. The Celtics don't need Irving to be a +20 player beat good teams. The Raptors need Kawhi to be. That's the difference between the two teams.