The current version of Java SE 6 from Apple should allow Adobe apps that require Java to install and run. (It's still needed for CS6 apps!)
However: CS3 is 8 years old: even if it does work on Yosemite, we've got El Capitan coming out in a couple of months, and the next version of OS X after that will definitely break it if EC doesn't.
I would advise anyone who doesn't want to get locked into Adobe's ransomware subscription contract to look for modern alternatives by other developers. Already apps like Affinity Design and Affinity Photo have been hailed as professional apps that are serious competitors to Illustrator and Photoshop respectively. (Disclaimer: satisfied customer of these products.)
Other apps are capable of doing the work.