I'd say that once more the most easy solution would be to include iso compatibility in the PCB (few extra holes and that's it) and to release the plates files (after the gb) so potential ISO buyers can get their own plate cut. Plus, ansi buyer might want a different material plat so they can get that as well
That would be a good start.
PCB-wise, ISO implementation is not a problem at all. What really is at stake here is the philosophy of this board - a clean "endgame" type board, and ISO support does compromise both PCB and plate integrity.
Talking to bunnies we came up with an idea. The PCB will be released under the Acheron project, and as such will be published under Open-Source Hardwarw guidelines, meaning anyone will be able to order extra PCBs. Mind you this was agreed from the start. The files will be completely published in their KiCad form once the GB is over. We could take advantage of this and implement ISO compatibility in a posterior version after the GB, so you ISO guys can run an after groupbuy among you. If bunnies agrees I could also make plate files so you can easily and cheaply order them made from FR4, in the same package as the PCB.
I could also customize the PCB to your liking, adding or removing key support, even making an "iso only" version. I am willing to do this redesign free of charge so we can expand the lifetime and support of the board for the users.
Then again, this is an idea we are discussing. The problem with it is that by knowing you would order an extra PCB after, you would not want to buy the original GB version, and we are not splitting kits.
We could also offer the ISO PCB and ISO FR4 plate as an extra kit, but that should be discussed more because it would take a lot more logistics and possibly more prototyping. This brings a big issue: let's face it, only a handful of the GB participants would buy this kit and the PCBA factory MOQ is 5 PCBs. So we already have an MOQ. Not only that, at the small quantity of five PCBs, the unitary prices of manufacturing and assembling skyrocket to possibly 80 bucks a PCB, meaning that the supposed add-on kit could easily cross 100 dollars price.
A third idea would be as you said -- make the original PCB ISO compatible. Honestly I think we'll avoid that since it goes against the board philosophy of being simple and clean.
We'd love to hear you guys on these ideas. We really want to accommodate as much people as we can but, then again, this is a very limited run and our priority is to deliver a clean, high-end keeb.