Heh, I've been mulling over this for the last few days myself, ever since I saw the item changes coming for s6. My problem is, I just can't find where to shoe-horn these items into a build unless I'm so far ahead that it wouldn't really matter what I built... allow me to explain.
Yorick has to build Tear, no questions asked, first item. Additionally, Riot has forgotten Yorick Mori to such an extent that he is the only champ that would go into lane with mana pots not getting a mana pool or regen buff. Depending on how livable this situation will be with the new masteries or perhaps a faerie charm start, I might seriously consider running mana regen blues on Yorick just to get close to where he is now. The new gunblade strikes me as something you want to rush in lane so you get the most out of it in laning phase, so after tear would be the place to put it (as an aside, I think the biggest abuser of the new gunblade is going to be Heimerdinger... he could rush it first item to become an unmovable, ungankable, unkillable object), but then you have to consider is gunblade a good replacement for trinity force as Yorick's damage item? After laning phase I'd say trinity is far superior, and if you get all three then that only leaves you two slots for defense after boots.
As for Essence Reaver, I did not realize the interaction it would have with Yorick's Q; if that is indeed the case, perhaps it could work as a pseudo-replacement for tear/manamune and is even more appealing with the increase to Trinity Force crit, giving you a way to build CDR without building defense, but I fear that even with these changes Yorick is going to fall into an unusable grey area of, "Can't build enough damage to be truly threatening while being tanky enough to survive"... of course, I won't say anything for certain without extensive testing come tomorrow.
Just my two cents.