There is still no word from Camel on why they have suddenly left the stage, but several users are already planning ahead to keep their apps running! Clif from Apptronica has put together a video walkthrough on how you can restore the Pro upgrade. This is the important one that lets you use custom presets. If for some reason you need to reinstall Alchemy, or want to run it on a new device, this is the way to do it!
Note: This will only work if you have purchased the Pro Upgrade in the past. Sorry new users to Alchemy!
Pro Upgrade Restore Instructions:
First off, if you previously purchased the Pro Upgrade, restoring purchases will activate pro functionality. You can confirm this by checking that the option to add custom sounds and the User library folder are available in the presets dropdown menu. This will not install the additional presets that came with the Pro Upgrade IAP, so I'm going to help you with that.
You start out with 55 factory presets. The Pro Upgrade content and Bonus preset pack give you a total of 188 presets. You can skip downloading and installing the Bonus pack, because this library includes those: https://www.dropbox.com/s/a5jaq8rsvet9hjm/AlchemyMobilePro-2-01.CamelSounds?dl=0
To install this, use iTunes sharing to drop this file into your Alchemy documents, then click on "Add custom sounds". The file will be listed under "Copied via iTunes" and clicking on it will restore the presets into your factory folder.
Clif even did a video of the whole process! This will not recover the individual IAP libraries, which cannot be shared without violating copyrights, so for that you'll need to make your own backups using iFunbox.