I don't see anything in the TPP requiring retroactive application of copyright terms. We'll have to wait and see how the various countries choose to apply the new terms. Applying terms retroactively is uncommon, but possible. We also have no idea when these countries are actually going to apply the new terms. It took the UK 100 years to apply the terms of the Berne Convention after signing it. If a country proposes a retroactive copyright extension as part of their compliance legislation, it is still possible to fight the retroactive provision (regardless of what BoingBoing says). In other words, it's way too early to start talking about deleting files from Commons. Even the URAA took 18 years from the time it was passed until Commons had to actually deal with it (due to the Golan v. Holder decision).