I don't want to sound like underestimating the greek, but not sure if his weapons (serve and FH) will be enough to beat Novak on HC in RL arena if they meet. It's the greek's weak areas of the game that are most problematic. He makes too many UEs, has weak BH and ROS, all which Novak knows how to expose it. Tsitsipas hasn't beaten him in a while I think, he is a good match up for Novak. Then there is also a mental aspect which plays a big part too.
Still it is tennis and you never know. Tsitsipas might show in a final playing the best match of his life and then anything can happen. He will surely need to play on extremely high level to hurt Novak here. That means all things clicking for him, serve, FH, BH, minimum UEs. If the greek can sustain that level for the most part, then he has a chance and we get to see a really good close match in the final instead of a one way road.