I am currently working on the new ACA500, which has the internal name "ACA500plus". It's a complete re-design, as one fundamental requirement of the old design has changed: While the old card was attempting to keep as much as possible in the 5V domain, the new card is working with "almost only" 3.3V components. Practically nothing of the old design is remaining the same, except for mechanical data, which is almost identical. It's a new design from scratch.
I'm working from bottom to top, with currently only the 68EC000 CPU running at 7MHz in syncronous mode, memory barely tested, but the good news is that both Rev.3 and NTSC-Rev.5 board play nice up to this point.
ACA1221 is in production. I'm waiting for shipment of the empty PCBs, which was delayed due to Chinese New Year holidays. The supplier keeps apologizing for the delay, but doesn't give any hard facts about a shipping date. They did ship the C64 Reloaded boards recently, so they are not out of the world. No promises about a release date from my side unless all components are really here and have passed incoming material inspection.
Zippy Zapp: That memory expansion is a bit larger than the popular 1.8M expansions were. The new design will support using up to 1.5M of such a 1.8M expansion. Those larger ones weren't popular at all (at least in Europe), so I would not regard them as standard. Besides, if you don't have the Gary socket installed, you just have 512k of the expansion available. The good part of that config is that you can use the ChipMap feature of the ACA500, which has already been verified positive on the ACA500plus (which may actually be called ACA500n when it's finished...).