With the incompatibility of iPhoto included with Mavericks and Aperture 3.4.5, Apple release 10.9 without upgrading Aperture. So I'm wondering, what are the odds we'll see a new version of Aperture vs a patch to restore compatibility?
Aperture runs fine. What the issue is is that opening a photo library with the version of iPhoto that is bundled with Mavericks updates that library so the current version of Aperture can't open it.
Apple has touted iPhoto/Aperture library sharing for a while. I don't see them changing that.
But are you running Mavericks and the Mavericks version of iPhoto?
Because I share the OP's concerns - Mavericks requires an upgrade to iPhoto, and when you run the upgraded version for the first time you get a warning that your library will be updated if you continue and will no longer work with Aperture.
I find it difficult to believe that Apple will leave the shared library feature broken. I guess we'll see an update to Aperture when Mavericks is released to the public - they couldn't publically update Aperture before the iPhoto update is publically released otherwise it would have broken compatibility the other way round.
I just checked and I'm still on iPhoto 9.4.3 with Mavericks GM build 13A598. I guess Apple must've removed the iPhoto update as it's not bundled in the installation and I can't locate it in my dev account as a separate download and it's not showing up in MAS either.