There used to be comps that dropped casters entirely early Stormblood with DRG-NIN-BRD-MCH and on certain fights people even ran triple melee. Double caster or double phys ranged with a single melee was also viable, but generally it meant not mixing SMN and RDM, both in damage numbers and buff synergy.

Double melee will remain supreme as long as the damage numbers remain melee-favoured. Right know I can see Pictomancer play in a pseudo melee position, especially if BLM gets sufficient buffs to damage on tuesday, allowing for double caster (high damage). You can also bring RDM or SMN in place of BLM for prog if you favour a caster raise.

Long story short, it's all about damage first, utility second and ranged advantage third. If double melee has no spacing or uptime struggles and keep the numbers high, it will remain meta.