if they don't do this alongside the remodelling they'd never do it. IT is precisely becuase they are doing the new models that they can slip in minor races - e.g. maag'har orcs, you've designed the new orc model, done hte animations tha't s a lot of workk, now you're working on the skin tones, adding a Mag'har orcs is just a matter of adding a set of brown skin tones, adding dragonmaw orcs just a matter of adding grey and black skin tones. Dress it up by adding an icon to the orc character creation screen that has a mag'har descritiopion and simply swaps the skin tones and maybe adds a tribal feature, something you can design whiles you're doing the orcs.
when you release them, do a mag'har narrative that adds to the orcs. you can intorduce the orcs, then add a few sentences about the ma'g'har or re-write a completely new narrative. Doing high elves is even easier, you're not even changing skin tones you're just giving normal blue yees instead of glowy ones. you don't need to finish the remodelling and then work on minor races. you do them all togehter.
doing all together doesn't mean you need to release them at the same time though. you could have done the orc remodel with the mag'har and dragonmaw variations, then just releas the orc, then later on the mag'harthen later on the dragonmaw if you wanted to do phased start zone or something more. you can maxmise your prfoits based on how you release these thing.
mind you you will get a spike in re-subscritipins and race changes, not to mention revived interest every time you introduce a minor race, players will keep laying looking forward to which minor race or remodel is coming next, and i'ts something you can do over the next 2-3 years aside from the content patches and upcoming expansions which can introduce whole new races and classes ina ddition to new zones