Again, depends on the presentation and execution.
Black eyes and glaives are nothing new either, but that's what made Nightwarrior Tyrande cool, right? Or even Dark Ranger which you want to be a class. Nothing is unique that couldn't be represented by Hunters or DKs, yet you still want a class dedicated to it right? You want it to be a class not because it's something new, but because you think
the concept has the potential to be explored as a new class . Now, apply this to what Devs are doing to plan a shortlist of classes for a new expansion
Potential for exploring themes and gameplay is the reason why I argue for any class to be playable. Not because of it being new or being a fan favourite, but because of what I think the Designers at Blizzard may want to explore next, and what journey of exploration they want to give to players for the expansion as a whole. Evoker exists for this very reason, as a means of exploring Draconic magic, culture and themes in a single playable class. Again, I defended their existence despite not caring about them personally, because I recognized the potential twinkling in the eyes of the developers. They dropped massive hints towards this.
You can apply this to all previous expansion classes too. Some were fan favourites, some were not even requested, but the common goal was all the same for every class - Potential exploration of new themes (related to a new expansion)
The strongest candidates for new classes will be defined by the story and setting plans for a new expansion. If a class can be written to fit a Titan themed setting, it will be more likely than a class with a rigidly defined theme, like Blademaster or Shadow Hunter for an expansion like the Last Titan. It doesn't mean Blademasters or Shadow Hunters are implausible, it means they're less likely for the foreseeable future.