Adam of ACK controls has stated that he is working on at least two new boards with the aim of running OS4.
The first of which is the PowerVixxen LT. This is an accelerator for towerised Amiga 1200 computers. It attaches to the trapdoor slot, and provides a PPC processor, mobility radeon graphics, and maybe some other goodies like USB and ethernet. This board has a lower end PPC CPU soldered on and will allow OS4 to run, while giving programs access to the original chipset for maximum compatibility.
The second board is the PowerVixxen TL, which is a standalone motherboard like the A1. It is said that it will have a CPU socket into which you can put an AmigaOne compatible CPU card (which Adam is also producing). This board is supposed to have a lot of expandability, and not so many features built into the board. I don't know too much of the specifics for this board, but apparently it has a faster memory bus and things which will make it run rings around existing AmigaOne boards.
Whether they actually are going to arrive or not is a subject of extremely heated debate... personally I don't know, but I'm optimistic. Possibly more optimistic than I should be, but then I reeeeally like OS4 and i'm hoping SOME sort of solution to the hardware problem happens.