Yes, there will be a wipe when the game transitions to beta. We try not to wipe unless we have to, but when there are major updates that require it, we will. This means it's not possible to project how many more wipes there may be between now and launch. And, yes, that means we will do a final wipe before the game launches.
Regarding Dregs, the testing for that will continue to be the focus on our TEST server environment. Those who want to participate in Dregs campaigns can playtest it on TEST.