Johnson, Norman J., Washington's Audacious State Capitol and Its Builders. Seattle: University of Washington Press, 1988: 35-37

As you can see, these images clearly show that both designers assumed that the isthmus would be built-out. I say assumed because the book clearly states that the isthmus was not part of the scope of the campus design project - and this was true even for the Olmstead's project, which was meant to be only landscape design in scope.

So, in all fairness, I do not think this completely answers the question of exactly how the designers would have designed the isthmus; it just shows that they did not assume it would be a park - they assumed it would be built out. In fact, the Olmstead rendering shows a diagonal park corridor between the campus and the edge of the core of downtown (today's Legion and Capitol, perhaps?), as well as a narrow view corridor through the built-out isthmus, similar to OLY 2012’s vision, I think. It was noted by Johnson, however, that this proposal was deemed unfeasible by the state campus commission because it would have been too costly for the state to buy the land from the private sector that would have made up the corridors. (I think we all need to keep that practical reality in mind when debating what to do with the isthmus - OLY 2012 included).

Lastly, and again in the interest of intellectual honesty, there is virtually no question that both Wilder & White and the Olmsteads appreciated the views to the North of the campus. Johnson points out that the views to the north drove a lot of the debate about the campus design and in particular, where to build the Temple of Justice.

Perhaps the designers didn't give much thought to the isthmus? I think it is fair to conclude that they didn't envision it being all park space. But it is probably also fair to assume that an isthmus populated with commercial buildings of the style and scale common in 1911 probably wasn't going to be much of a factor in their design considerations anyway.

Would they have been disappointed to see the Capitol Center Building in all of its Miesian glory planed right in the center of the view? Perhaps. Would they have thought that a 65-foot mixed-use structure on the left edge of the isthmus would have destroyed the view? Who knows? But perhaps the best question to pose here is: what would these designers have thought to be an appropriate use of the isthmus had they understood the extent to which the automobile was to redefine the urban landscape and our way of life? With climate change and a carbon footprint to consider, I am not so sure the designers would have insisted on saving the waterfront views.