Guild Wars 2

Tactics – Phalanx Strength : When you grant yourself might, grant it to nearby allies as well (6s of might)

With the new traits coming out would a 20/20/0/30/0 build be viable with the ability to have multiple might stacks for the party with a warrior using the greatsword?

The build is going to be something dumb like this. Its sole purpose is as a might buff kitten.
http://gw2skills.net/editor/?vIAQNAR3ej8cU5ZtHefQHiAwUAgjCoYSVgu0jwIzMA-z0gAUWgIR4KvIasCCgdA-w

No.

Any Elementalist with a brain covers might. A Warrior running Phalanx Strength will be stacking less Might than an Ele, as well as doing less damage – what’s the point?

With said Elementalist, Forceful Greatsword is already a bad trait because of the short might duration, you don’t want to override the Ele’s might with this 6s might.