Blizzard FINALLY seem about to do something about the 2v2 Arena queues:

It's an issue, and we're aware and will be making changes to help with the wait times. The change will require a patch, but will not be a part of 2.3.2. I'll state a vague "future patch" just to be safe, but we're hoping to resolve the wait times as soon as possible.

The change will make it so that more instances can kick up in a shorter amount of time. Which doesn't necessarily mean there can't ever be a wait again, but it should drastically decrease them. Of course, prime-time 2v2 is still going to be run the most and susceptible to the longest wait, but our hope would be to make "the longest wait" inconsequential.