Apple has now confirmed that its current Aperture app for the Mac won't be available to purchase once the new Photos app is released to the public sometime later this spring. The Photos app was made available for OS 10.10.3 testers and developers last week.
While Apple had already said it planned to retire Aperture in favor of Photos during the 2014 WWDC in June, the company has now updated the software's website to state that it will "no longer be available for purchase from the Mac App Store" when Photos is launched. Folks who have already bought the software will still be able to download it from their purchases tab.
Apple has yet to give a specific date on when Photos will be launched. We've been testing the early version of Photos already and checking out how the transition from Aperture to Photos will be handled.