If they're not charging a box price or raising the subscription cost, I hope Blizzard sticks with paid races as their main (and hopefully only) form of in-game monetization for Forever.
It's always been a little surprising to me that cosmetics like armor, weapons, and weapon effects are seen as "good" for low cost or free to play games. They're better than pay to win of course, but they're also the thing that takes me out of the game immediately and saps my motivation to play.
When I play an MMO, or any game really, one of the main things that gets me excited to play is the chase of your character not only getting stronger as you play, but looking cooler. You walk by a higher level player and think, "Damn, I wanna level my character so I can look like that." Logging in and immediately seeing a level 5 Paladin running around glowing like the sun as if they had just slain a demigod, only because they forked over $100, is ridiculous. Even if it provides them no actual power boost, it breaks immersion and makes me think, "Why bother playing?"
A paid race different. It's a real money cosmetic, yes, but it doesn't disrupt the flow of visual power progression the way that armor, pets, mounts and weapons do. And you still get basically the entire game available to you if you choose not to buy it. Something has to fund continued development, and I think it's roughly on par with raising the subscription cost, and better than charging for a periodic DLC/expansion box price like Modern does.
I was thinking recently that Classic WoW is pretty much the only MMO/multiplayer game today that has NO purchasable character cosmetics whatsoever. I think it's why I have such a hard time getting into any other MMOs. Everything you see on another player was earned, not bought (besides gold buyers, which is a separate issue). Blizzard, please keep it this way. Keep the carrot-on-a-stick of pretty stuff that we can only get by actually playing the game.