Would people play a 'Spellblade/Mystic Knight' themed DPS Job?

[Zairava]

I absolutely would, personally. I haven't been vocal about it but it is something I've been wanting for years.

If they hadn't deliberately and consistently removed all the elemental damage/resistance mechanics that used to exist in FFXIV it would be more likely.
But as things are now? Not very likely.

Realistically they could just make everything deal magic damage and have the elements be the core of the job's gameplay identity. (As in, the elements would be enhancing your abilities. Whether it's raw potency, debuffing the enemy and making another element more powerful with said debuff, building towards a much stronger burst potential, etc)