Somewhat cynical question, but is the 100 year aspect of this study anything beyond a marketing gimmick?
[1]: http://www.huffingtonpost.com/2013/08/11/how-this-harvard-ps... [2]: http://longnow.org/
If you are applying for funding as part of a 100 year study, you won't get continued funding unless you put in the effort up front to design the data acquisition correctly.
A hundred-year project will be able to offer more permanent assignments. That creates less 'publish or perish' pressure. It also may attract scientists with different character traits who wouldn't be able to compete in the rat race to tenure.