Well... I think the dev probably polished 2/3 lines... With the following issues:
1. Group content might be easy enough to tank in Overpower. Would that really surprise anyone, given the last patch?
2. The focus on raiding has been disappearing, and without raids... Does anyone need a tank with high mitigations?
The biggest challenge for good guardians in the past was threat generation, and there was a certain amount of build-tweaking you could do to help with that. Or you could tweak your build for higher mitigations... If threat is no longer an issue... You'd expect everyone (smart) to have the same builds... Stack as much mits as you can, hitting good breakpoints for incoming healing and morale.
BUT... as to my 2nd point... Typically group content doesn't require a tank with amazing mitigations... I mean typically a captain could tank any group content, with mobs he's unable to grab just getting picked off first by good party members. SO if you don't need those extra mitigations for group content, then what is a guardian going to do? He's going to get bored and probably go tank in OP like we used to... And since the raid isn't going to come out for 3-4 months (if it comes out at all)...
Well bottom line I think tank-line will be thought out but un-used because of content. DPS line will be used a lot. FOS line sounds like the dev didn't know what to do with it (Nor do i blame him) and it will probably be used by guardians because they don't need tank-line mits in group content, and they're bored.
All in all i'd prefer they not have made threat changes... But maybe it's for the better, because we've all had too many guardians that didn't know how to tank. The good ones will still understand mob-positioning and movement... If that ever becomes a factor.
Not too excited, but at least we're getting an update for once.
105 (Captain, Champion, Guardian)