Just a quick sanity check...
One can absolutely connect a DCB-capable switch port to a switch port that does not support DCB. Is this a correct statement?
It seems like it should indeed be the case. The DCBx protocol is meant to exchange DCB capabilities between ports. So if one switch port does not support DCBx, it will simply ignore the DCBx packets coming from the other switch. And if thats the case, there shouldnt be any issues....