Framework is committed to this form factor:
and have released an upgraded mainboard (Intel 12th gen) with the exact same form factor.
If they were to release a mainboard in a different form factor, all existing Framework laptops would be obsolete and incompatible. That would anger customers and would invalidate their mission to be sustainable - their laptops would not be reusable at all.
Their intention is to make this mainboard form factor an industry standard and develop an ecosystem around it. The designs are open sourced:
so future mainboards will follow this form factor.
As for AMD, the company is definitely aware of it (look at all the posts). There must be reasons why an AMD mainboard has not been released, but Framework wisely does not announce anything until it’s actually in production. So we don’t know the reasons why and can only speculate. There has been some good speculation, especially recently: Desperately Missing - #20 by lhl (my personal guess is that this is the most accurate reason) but it remains just that, speculation.
We can guess that Framework wants to sell AMD mainboards (and RISC and ARM as they’ve stated) but they’re not - there must be reasons why and we simply don’t know why.