Some ideas:
Gold is replaced with either Metal, Crystals, or Stone. Or, perhaps, all of them - like, "Ore" or "Shards" or something. Either will be mined from small deposits scattered across the map. Mining will be much more similar to the way Lumber is harvested - the worker wont enter the chunks\deposits but rather harvest from it. Upkeep will not be used.
Orc: Peons will harvest ore just like regular peons harvest lumber in WC3, same for lumber. Peons can mount a boar from the pig farm, reducing the amount of food provided by that Pig Farm but increasing the peon's attack and movement speed, armor, health and damage.
Ogre: The Ogres will have two kinds of workers - the Masons and the Lumberjacks. The Masons can build structures, mine from deposits and repair, while Lumberjacks would be able to only cut lumber. If the War Forge is built, you will be able to convert Lumberjacks to Axemen, by attaching a second blade to their axe and making the handle longer(so it becomes rather a Battle Axe) and forging some light plate armor for them. Axemen no longer are able to harvest lumber, but are able to deal much more considerable damage and would have much more armor than the Lumberjacks.
Arrakoa: Apostles will be able to summon Slaves(Slaves will be captive Arrakoa, enemies of Terokk, non-believers, rebels). The Apostle must channel if the Slave is to remain under the Apostle's control, held with magical chains and a weak mind control spell. The Slaves can gather resources, but are very vulnerable and weak. In addition, if a slave moves too far from it's Apostle, or if the Apostle stops channeling, the slave turns against the Player, attacking it. Apostles can be ordered to "Unsummon", which will stop channeling but will also unsummon the slave, returning it to... umm... the magical slave-pens which exist somewhere. Apostles can summon buildings very similar to how Undead summon buildings in Warcraft 3, but the Apostle channels while summoning. If the apostle stops channeling or is killed, the building is destroyed(and the resources are returned). Apostles can sacrifice themselves, transforming into Shadowy(or Time-lost) Devotees(or just Apostles), which have a moderately powerful ranged magical attack, but are as vulnerable as they were when they were mere Apostles.
Draenei: The Draenei have two worker types - the Gatherer, which can gather resources and has a weak attack, and the Architect, which can build structures and has an even weaker attack. When an Architect builds a building, it will stay inside it and will slowly repair it when it is damaged(in the cost of resources; the Repair ability is auto-cast, so you can cancel it). You can order the Architect to get out of the building, however this will stop it from being able to auto-repair and it will make the building only half-functional, making training units, researching updates, attacking units(e.g., the tower) and any other activity the building does slower and less effective. Architects can pick up some armor and a war hammer during a battle from the nearest Town Hall(Refuge would be a nice name), while Gatherers can pick up a bow and some arrows. Works like Militia.