When I brought this up at the CB8 meeting held on Roosevelt Island I was basically shushed by the pro-memorial crowd that the first branches of the trees woud start at 7 feet in height and the views below that height would not be obstructed. True if you walk under the tree you can regain the view of the direction you are viewing but you still lose the 360 degree vista previously afforded. Somehow my neighbor could not understand that I felt the loss would be most felt from within the raised grassy area that is to be flanked by the two rows of Linden Trees.
The below picture immediately below is of the current view looking West torwards Manhattan. The picture was found HERE on Flickr. Note that your eye does not only look straight out at a zero degree inclination but also upwards at varying degrees to take in the entire skyline. The picture below that is my version of the picture once the Linden Trees really start bearing their full leaf growth.
Remember it was stated at that same CB8 meeting that once the Memorial is created that no funds are being put into a trust to care for park or its upkeep. So while the Memorial at its dedication or soon thereafter may include great views (if baby trees are planted) or even if adult trees are planted which are well trimmed like these from a Berlin Avenue (properly thinned to allow some views between the branches) the full unobstructed views will no longer be available.
In time without proper pruning the trees left untended may resemble the thick leafy growth of this picture. Granted this picture is of a forest of Linden Trees and not one single row but you do see how these trees can grow thick leaf cover to some pretty good heights.
Each of the two above images was found via Google Images by simply searching using the term "Linden Trees"