The plan is, and has been for some time, to convert the PPA builders to a specialised OpenStack cloud ("scalingstack") rather than investing any more effort in the current setup. Quite a bit of work has gone into this by Canonical IS, but it's rather a complex project and is still in progress; I can't give an ETA, although we hope that we won't need to struggle along with our current setup for too much longer.
That sounds pretty cool. Is there any preview of the setup there? I was thinking about setting up a virtual builder just to make it easier to suspend my laptop. I'd rather do it a supported way than a bespoke one.