[@Sho Minazuki]: I think that's more inherent in the type of game, isn't it? If we're using MMOs as a point of reference (at least as a starting point), then I'm not sure to what degree you can make it engaging beyond making the subarchetype consist of what are essentially physical casters (instead of mobile ranged DPS without cast times), and even then the way you've set up the class makes it really linear and hard to add anything on to. Like, if you have the core kit at some leveling point, then how do you add skills onto it? If every expansion would add something (or a few somethings) new, it becomes very difficult to given them new tools (as you yourself have stated here).

My personal recommendation would be to take the fundamental ideas of what you want in the class (as after a bit of though I think a physical caster-esque class could be interesting, designating them as 'snipers' is a bit of a misnomer) and break away from the 'box' that is the archetype you've started with. Since the class needs (new) room to grow once the RP starts, which way do you go from here?

That's my suggestion in this case.

[@VitaVitaAR]: Will go into a more detailed analysis once it's done, then.