Quoted from this interview: https://venturebeat.com/2019/11/07/world-of-warcaft-shadowlands-looks-to-address-battle-for-azeroth-biggest-problems/
Specifically:
GamesBeat: Will Frost Death Knights be able to use two-handed weapons again?
Day: I want to say that’s on the “would like to do” list. I can’t promise anything, but I know that’s something we’ve heard a lot of feedback on.
Keep that feedback coming 
Keep letting our voices be heard on this ! Hopefully a solution can be made!
I hope they don’t being back 2h frost. DW gives the spec much more of a unique identity
Would you have a problem with it if it was purely cosmetic? So dw stays?
Hopefully they follow through with it
My feedback is that frost should stay dual wield.
I would love 2h frost again. I miss being a juggernaut in the image of our father 
I love unholy and the thematics of raising the dead, but the gameplay doesnt feel great to me. I’d rather it be about summoning undead than all the diseases and festering wounds.
Ahhh, the imagery that two handed Frost evokes is really the ideal Death Knight. Mechanics and balance aside, when I hear the words, “Frost Death Knight,” I picture a slowly advancing juggernaut, trudging ceaselessly through a blizzard toward his target, the remorseless winter draining the will power and strength of the fleeing opponent. I envision this plate wearing messenger of frozen death carrying a gigantic runeblade, held in both hands, each attack slow, deliberate, and carrying the weight of a glacier behind it. Two handed Frost coming back as an option would please me greatly.
IDK why, but i was more optimistic until reading this. Not knowing anything was somehow better than hearing someone working at Blizz saying “Would like to do”, and “Can’t promise anything”.
Even if it’s purely cosmetic, 2H should be brought back. One of every 2 or 3 posts in this forum has a mention of bringing back 2H. It’s disheartening to see the game devs not take player feedback that is this extensive, to heart.
I just dont understand the people who say it should stay gone. If u have both dw and 2h options who cares? Besides if blizz can balance rogue skills doing more damage with a dagger and less with a sword, logic would say they can do the same worh 1h vs 2h.
I say let it do both,
While I don’t like the wording, I’m glad they’ve at least finally acknowledged the desire for 2h Frost. Hopefully that’s the first step.
Agreed, I really prefer DW Frost!! Please keep DW for Frost Blizzard!!!
The forums are a place people come to complain. Plenty of Frost DKs are out there enjoying DW without the need to cry out for a change. Don’t forget them.
I do hope that for you and the handful of other Frost DKs that prefer it, DW stays an option.
No one should have to lose out on their preferred style.
I don’t want it to be an option, I want DW to be mandatory for Frost.
Name me other specs that get to pick if they can DW or 2H it?
Okay well you’ve convinced me.
Maybe DW should be removed.
Name another spec you can pick between DW and 2H?
Well since they’ve pruned all the specs that could, none.
The unpruning comes.