Today's deploy will prune out a lot of unused test code that's accumulated on the PBE version of the client to bring it more in line with what we ship to live each patch. This is an under-the-hood adjustment which shouldn't change much for you guys - basically, the patch will tell your computer "Hey, we aren't using these files any more." The main difference is that the Replays menu will be taking a leave of absence from the PBE client.
**WE ARE NOT CANCELLING REPLAYS!** The big problem we're still facing is that we need to make sure every region worldwide has servers that can handle the strain before Replays can be released. Taking them offline for a while gives us a few more options to explore in terms of getting to where we need to be (such as adjustments to how our servers might need to interpret or access Replay data). You can expect Replays to return to the PBE further down the road when we're globally better positioned to support them.
Keep an eye out for more information - when Replay testing resumes, we'll let you know here.