I don't think there's enough water on the planet for 200 meters of sea level rise
Also what would cause waves to break at that height? If the pyramid was actually underwater it should just be getting swells, not breaking waves.
We're in an Ice Age right now (defined as there is ice at the poles, which is not always the case), so over the next 50,000 years we will likely have melting and a few meters of sea level rise
I did a little more internet searching
You are right that the top of the Great Pyramid is roughly 200 meters above sea level
However, if all the world's glaciers & ice melted, internet search tells me it's only about 70 meters of sea level rise. The Giza Plateau is 30 meters above sea level, plus the Great Pyramid is roughly 140 meters tall, so the "wave erosion" should be at most 1/3 up the pyramid, not 2/3+
Excuse me, Giza is 60 meters above sea level. So the maximum possible sea level should be less than 10% up the base of the Great Pyramid.
So the damage shown on the pyramid does not come from wave erosion.
