With this new venture, I just do not see AF and KL wanting to sell tickets on connecting CO flights. Their website and systems will push connections at DL and NW hubs. They will only want to market their flights out of EWR and IAH as orginating flights for connections at AF/KL hubs.
The purpose of an alliance is that alliance partners sell tickets on the other partner's flights. The venture is significant in that a complete DL/NW merger has now been officially ruled out. But I could see DL and NW merge their FF programs and even their websites, sometime in the future. Yes, the venture is for Atlantic flights at this time, but it could expand.
CO OnePass was the combining of Eastern's and CO's FF programs - but there was no merger.