Yes, but the conclusion does not follow from this goal.
There's no reason that an open format will be readable in the future. If I define some document format, build an application that reads/writes it, and publish it to github with GPL licensing, then in all likelihood it will be forgotten completely in a decade. My inability to gain users will ensure that it withers.
On the other hand, even if the .DOC and .XLS files made by Microsoft are proprietary, they've been reverse-engineered and are well-understood; the .DOCX and .XLSX file formats are even documented. Because they're so universally used, out of necessity, someone in the future will be thinking about how to read those old files.
So being open might make it more likely that something obscure will be readable in the future. But I don't think it's nearly so strong a likelihood as what demand from an army of users of proprietary software will lead to.
The point is, in the distant future, someone will be able to use the specification for ODF and read a document that complies with the standard. All aspects of the file will be reproducible, including metadata, tables, etc.
And as I said, open formats are just one approach. The approach that the US Courts and the State of Washington takes (conversion to PDF/A or TIFF) is a valid approach too.
For instance, it does not specify how formulas work in spreadsheets.
You can't store the full spec of a format that's not fully documentes nor keep a runnable reference implementation that has only a binary executable (unless you also preserve the computer it runs on). But then you have turtles all the way down.
Isn't it much easier to just have compilable source code?
Hell we cracked the german army and naval codes without even really knowing what a computer was.
He did talk about making "public knowledge accessible in the future". Public institutions have a moral and legal obligation to preserve certain items for posterity.
The problem with a proprietary application like iWork is that it uses a closed file format that may or may not stand the test of time. I've worked with archivists in government institutions, and they are already struggling to preserve digital documents produced as late as the 1980s.
As a citizen, I have the ability to learn from the primary sources that are hundreds of years old. One of my college friends spent a semester examining the papers of colonial New York State governors and looking at maps and treaties produced with Indian nations.
Unfortunately, the chances are very high that our children will not be able to read many of the important papers produced from the 1980's through today. How accessible will WordStar documents be in 2060? Or Excel XP spreadsheets in 2100?
There are different approaches to improving the current situation. The State of Washington chose to convert everything from native format to TIFF or PDF images. South Africa and cities like Munich are choosing to mandate the use of free and open native formats. There are ups and downs to each approach.