Lets face it. The three class model dates back to as far as fantasy and sci-fi was a thing. The whole warrior, mage, rogue trio is a common trope.
That being said:
Titans = clone commandos/mandalorians
Hunters = smugglers/bounty hunters
Warlocks = jedi/sith
Examples:
The blue titan in one of the original trailers looks remarkably similar to the blue mandalorians from KoToR
Many hunter items hold close resemblances to the bounty hunter luke skywalker impersonated in Empire Strikes Back
Warlocks... Yeah... I don't think this one needs an example...
Let the flaming and exclamations of fanboyism commence!