When Moraine left Tar Valon, she knew she was undertaking a very dangerous mission, IIRC from New Spring, the black ajah could well have been after her and if she were to succeed in finding the Dragon she would undoubtedly be in the firing line of the Forsaken.
I would suggest that Moraine arranged for Lan's bond to be passed to Myrelle upon her death to prevent him from either dying in a vain attempt to avenge her or from returning to his lone war in the blight and, probably, dying there. Myrelle was then to help Lan recover from Moraine's death and then pass him off to a newly raised sister to continue the fight against the shadow. (I think this is pretty much common knowledge, nothing new here.)

I doubt she anticipated meeting Nynaeve in the Two Rivers, and seriously doubt she expected Lan to fall in love. However, once this happened it became clear that Nynaeve would not let Lan go, especially if Moraine were to die. As such, I would say it was more of an inevitability than a plan that Lan's bond would eventually pass on to Nynaeve. Indeed, Nyneave has frequently made her desire to have Lan's bond passed to her very clear, as well as a few other nasty thing she would like to do to Myrelle!