Music, and Brook specifically, has the potential of being the key here if:
1. music is used to snap Gunko back to take control of her body, even if just for a few seconds, enough to stop IMU from killing someone important;
2. if IMU truly is from another dimension, then Brook's conjuring of "hell ice" through music might either grant the SHs access to IMU's dimension, or interfere with IMU's possession from said dimension.
That would be fucking awesome. Nusjuro is a skeleton horse swordsman that freezes people too and seems to attack their soul like Brook does, so I wonder where Oda is going with that too?
As you mentioned the "hell ice", which can go with the notion of "he'll frozen over" or even the Buddhist freezing realm of hell and also the Norse equivalent of it too, Niflheim?
Binks Sake is gonna have immense importance by EOS, as in plot encompassing and changing entirely. Marco The One Piece Theorist had an amazing theory on how this heavily inspires and foreshadowing Shanks character and role, how it relates to Journey to the West that immensely inspired One Piece and thus how extremely important West Blue is to One Piece, which is also where Brook is heavily associated with, along with Moria, Perona, Shanks and Lafitte I think hmmmm.....
Also the story of IRL hero/God Joyboy from West African or I think Carribean culture who was famous for his drumming and affecting people IIRC. And we have Drum Island, Will of D, Luffys drum heartbeat as Nika, Luffy using Dawn Cymbal in Nika mode, rubber being the cover for drums etc.
Then there's the Indonesian King JAYAbaya IRL (Also Joyoboyo) who was said to see a century into the future, to predict it accurately supposedly.
Music being the key really relates immensely to Film Red and Uta with her singing fruit summoning the demon king, who was unstoppable, indestructible even for Shanks.
@jinz has their amazing, detailed theory on how Gunko and Uta are very identical and ifs getting far more unavoidable and thus noticeable now too.
Luffy really wanted a musician for the crew around Jaya I think it was? Or Skypeia?
Brook has always been extremely important and thus necessary to the crew despite what his shameless, ignorant haters say.
Music will probably be needed to "soothe the savage beast" sooner or later too. The kids being controlled by Gunko and led to their deaths yet saved by music is an ironic twist and thus reference to the Pied Piper of Hamelin story too.
Brooks music can strike and manipulate the soul along with his ice from the literal underworld/hell and Oda has thematically inspired him on Charon, the ferryman of the River Styx, the river of the dead/souls and thus Hell ofc.
Brooks music can cause hallucinations/illusions, hypnosis and wrench out souls from Big Mom's fodder homies. It's all coming together, like a medley or any composition even.
I've always deeply loved this song for decades and associated it with Brook for the same time too, it feels extremely fitting:
Let me tell you a story to chill the bones
Out of things that I saw
One night wandering in the everglades
I'd one drink but no more
I was rambling, enjoying the bright moonlight
Gazing up at the stars
Not aware of a presence so near to me
Watching my every move
Feeling scared and I fell to my knees
As something rushed me from the trees
Took me to an unholy place
And that is where I fell from grace
And they summoned me over to join in with them
To the dance of the dead
Into the circle of fire, I followed them
Into the middle, I was led
As if time had stopped still, I was numb with fear
But still I wanted to go
And the blaze of the fire did no hurt upon me
As I walked onto the coals
Then I felt I was in a trance
And my spirit was lifted from me
And if only someone had the chance
To witness what happened to me
And I danced, and I pranced, and I sang with them
All had death in their eyes
Lifeless figures, they were undead, all of them
They had ascended from hell
As I danced with the dead, my free spirit was laughing
And howling down at me
Below my undead body
Just danced the circle of dead
Until the time came to reunite us both
My spirit came back down to me
I didn't know if I was alive or dead
As the others all joined in with me
By luck, then a skirmish started and took the attention away from me
When they took their gaze from me was the moment that I fled
I ran like hell, faster than the wind, but behind I did not glance
One thing that I did not dare was to look just straight ahead
When you know that your time has come around
You know you'll be prepared for it
Say your last goodbyes to everyone
Drink and say a prayer for it
When you're lying in your sleep, when you're lying in your bed
And you wake from your dreams to go dancing with the dead
When you're lying in your sleep, when you're lying in your bed
And you wake from your dreams to go dancing with the dead
To this day, I guess I'll never know
Just why they let me go
But I'll never go dancing no more
'Til I dance with the dead
The Dance of Death is a memento mori, a Latin phrase meaning, 'remember that you must die. ' A memento mori is a creative theme and philosophical ethos designed to emphasise the shortness of human life and remind the audience of their mortality. (Danse Macabre too.)
One of Holbein's first great triumphs, The Dance of Death is an incomparable sequence of tiny woodcuts showing the folly of human greed and pride, with each image packed with drama, wit and horror as a skeleton mocks and terrifies everyone from the emperor to a ploughman.
This is gonna very extremely relevant again soon with the Gunko reveal now too:
For those who hate Brook, who called Thriller Bark Filler (Bark) just like people called Skypeia irrelevant, self contained and Filler, shame on yourselves. You genuinely don't understand the story, Oda and his intentions, expressions and motivations.
You have no idea what's coming and it's gonna be glorious to see all the slander age horribly as it's done already now.
I strongly believe Jinbei, Nami, Robin, Brook at least will be needed to find and access Laugh Tame regardless in their own ways.
Also fun fact, since Jimbo is a WHALE Shark Fishman, he's not only sort of similar to Laboon BUT he cam talk to whales and understand them and is close with whale sharks and such.
Chopper can also talk to animals and translate them.
Guess what this means? Brook and Laboon can talk to each other properly! Not just with music, body language and such! Actual conversation! That is PRICELESS and it's gonna be EXTREMELY EMOTIONAL when that happens!
Also this has aged spectacularly well in a whole new meaning and emotional, tragic depth now too:
https://www.reddit.com/r/Piratefolk/comments/1jkwqim
AND Gunko saying she fears Nika makes much more sense now, as it was Goonerona Simpu talking through her ofc! Imu-hotep in "The Mummy"! (Gunko looks like a mummy and thus wrapped in bandages).
At this point, Oda saw our theories of Gunko being Victoria, Lami (Laws sister) and whatever and said LOL, YOU FOOLS HAVE NO IDEA WHATS COMING!
FINALLY after that mammoth easy rant, I think it was Shinichi or someone else who said she's using Brooks fencing style, his rapier? How bittersweet and ironic. Like father, like apparent daughter.
But I digress anyway ofc lol.