BLU can be a full job. Here's how:

[MartaDemireux]

I'm guessing it wouldn't be an incredible challenge balancing BLU for late/current/end game content, with the expectation of working with a full kit just like everyone else. But, they get access to that full kit everywhere. Or, on the opposite end of that, the nightmare of balancing around a BLU that hasn't unlocked their full kit. (obviously now I'm just rolling back around to the old argument of how to assure BLU has the skills it needs, so I'll cut that off now, no need to retread that one I'm sure)

This is where the range of power - or a point system of sorts - comes into play. As long as the BLU meets the minimum, it should have no problem. Whether or not the kit is fully unlocked wouldn't matter, as the BLU would be restricted from entering until they met that minimum power paired with the fact that they can only have 24 spells set at any one time. Future spells would likely give more playstyle options rather than "necessary" abilities; this way any given BLU could play the way they want, whether that's as a DoT specialist, ranged, melee range physical spells, tied to simply one or two elements etc.

As for "necessary" abilities, the solution to that is tie to them to job quests like Glower, or to totems like Off-Guard.

And for the part about low-level instances/1k Needles, it would entirely be possible to lock spell list #6 to being level 50 or higher.