that's exactly what i said
in order for the mobo to have ddr3 support when zen itself does not support it, the controller will be on the motherboard. thanks for restating it with caps for emphasis
zen itself will not support ddr3 as amd has made very clear, but since history tends to repeat itself, someone will make a zen mobo with ddr3 support for that small niche of users who desire it. clearly the op is such a niche user and would like one.
it's a bit premature to declare ddr3 dead to amd considering the same thing was done for ddr2 when ddr3 came out. as was ddr1 when ddr2 came out and so on.
but i'll just go away now and let you believe it won't happen again when it has happened so recently with skylake. i mean would be stupid for me to expect it to happen for zen as well.