Did the devs explicitly mention that BLU can't raid?

[Lambdafish]

the question is, will it eventually be able to do POTD and what will it's effect on soloing it be?

I imagine any new PotD that comes out in 5.0 will be designed with BLU in mind. The reason it can't do current PotD is because the two systems are incompatible (because PotD is based around skills gained at certain levels).

This could be retroactive as well, but I wouldn't expect it until new 5.0 content comes out