(map is just a hitn what could come. Expanding in which direction is not set in stone and also not how the "map borders" will look like. The maingame borders in the darklands are also a bit wrong)
Just wait for one of the expansion. Besides Lustria we could have Lizardmen in the southlands or on the dragon isles in the east. But best bet is, we will first see them *when* not *if* they expand to the west. Right for this game, no chance of official playable Lizardmen. After Bretonnia is made playable the best next DLC candidates for the old world are
-Beastmen
-Wood Elves
is this the real Warhammer?
-Skaven [but since they are so popular, they would be a better choice for expansion. Mabye even a PreOrder DLC again ^^}
-----Red Dox