All I know is that many people here boxed long before click functionality was discovered... though granted they were mainly doing single class.

As with any changes that come along, we will figure it out as a community. I am already contemplating moving from a 2 dps button setup (i currently have 1 button for single target spamming and 1 button for multi target spamming) to having a button for each character and managing different spells / procs with modifier keys... my wrists might fall off doing that though.

If they kill click with 4.0 at least we'll have some time to figure it out before the expac drops.