What do you need support for?
I don't see why CS6 would stop functioning. On a Windows PC for example it's still possible to run every Photoshop version ever released. You should not have to worry for a long, long time.
CS6 won't stop working but there may be software conflicts that won't be addressed in the future when the support stops.
For the photographer new cameras RAW files at some point won't be supported by CS6.
Then you either upgrade or convert all your RAW files to DMG first.
Not the end of the world but an inconvenience.
Adobe broke a promise.
They said you would be able to ALSO upgrade in the normal way if you didn't want to go with the monthly subscription.
As a photographer I don't need the newest features.
I used to upgrade every other version.
Now I don't upgrade a all.