When there will be a business case. That means, when there will be people willing to purchase Linux versions of Adobe/Autodesk/whatever apps, but not their Windows or Mac versions.
Normally, when people need Adobe/whatever, they will purchase also whatever OS is needed to run them - if you are getting expensive pro apps, 130 EUR/OS license (pro/oem/before VAT) is a rounding error. To Adobe this signals, that the porting effort would be a wasted effort, which they can save and earn the same revenue anyway.
So it is more realistic that some competitor appears, fills that demand and grows somewhat, before established vendors notice.