Quite a few end up surviving.
Sylvanas survived.
Jaina survived (and we’ll never hear the end of it).
Garrosh survived (then died in a quest next expansion).
Mekkatorque survived.
Kael’thas survived (then died the next dungeon).
Illidan died and came back anyway.
Kel’Thuzad is basically a demented jack-in-the-box.
This might hang on what you think of when you say leader. Is it a title or a description?
Title: Yes, he was the leader
Description: No, in general, he did not have the support of the Goblins.
Gallywix was handed power, given the title. So, he was actually the leader. But, for the most part, he didn’t really have the consent of the governed. Meaning he wasn’t really leading anything.
Either way you see it, Gazlowe is now the leader. Gallywix left any claim to it, likely because he knew he was no longer being propped up. It seems like it was a choice of leave quickly or be deposed.
To be fair, he did say “most.” Which is true. 
Personally, I suspect he will die because there isn’t much more for him to add to the narrative. Likely 11.1 is going to firmly establish Gazlowe position. He is going to best Gallywix and show himself the smarter/better one. Goblin players will get final closure on the events of their introduction quests. Beyond that, what would he add to the story? A recurring ‘you foiled me again’ villain? What point would he even serve going forward?
True, but most of them do die.
Description and actions. Titles are just titles. I Mean, I can call a chicken the leader of Venture co and that would be considered “canon” but in actual context, we all know that chicken is not the leader.
Oh, I get the sentiment. I think it just gets a little more complicated than that. It was more than just a title. Gallywix did technically have the authority and ability to give orders. And he did give some. Sure, he was propped up by Horde Warchiefs. And the Goblins as a whole did not really support him. But there was authority invested in him.
Unlike the chicken, he did have the authority and the ability to give commands. So, he was a leader in that sense. But, he didn’t really lead much and the Horde Goblins didn’t support him. So, in that sense he wasn’t really a leader.
My take is he was a leader in title and authority (until he lost the external support of a Warchief propping him up). He was not a leader in practice. And certainly not who the Goblins wanted to be lead by.
It was so weird that Thrall made him leader when he saw us trying to kill him. If they didn’t want to make the player character the leader, Sassy Hardwrench was right there!
Then that would have allowed gallywix to be more of an antagonist and be is horrible fun self to the Goblins. He would have been a great recurring villain. Sadly, they thought it would be more funny him as “leader” but that just got us to being ignored.
‘Hey, that guy that stole from you and tried to sell you as slaves, he is your leader now. You have to do what he says.’
Yah, it was weird.
And I had forgotten about her. Honestly, a Goblin leader with the name Sassy would have been kind of amazing.
Aye, and she would have made the most sense because she literally was our right hand. Also it is sweet that if you play a goblin character and visit her in STV, she gets super happy that “The Boss” survived and became even bigger and badder than before.
Gallywix might be “leader” but storywise of the Bilgewater Cartel, the goblin PC was always “The Boss” and Gazlowe a great partner.
More like, “I have no answer for this”.
I mean, you suggested that others couldn’t even understand your points (which is ad hominem) . I pointed out that you were making negative assumptions about others (which were also wrong), and called out the issue of even assuming you had the right to make such assumptions. I didn’t this by referring to what you said. Which is not ad hominem.
Gazlowe is boring though…?
No he isn’t. He just doesn’t get screen time. Dude used a gnome as a hostage and used him as a meat shield to get through a shield. It was funny. Dude blows up things as well and nickle and dimes people who aren’t thrall but he does pay his employees.
This is how I know you’re not into the goblin story and just follow the meme of Gallywix instead of the actual character
Ooh ignore me too, Jordlen. I blocked your other alt.
Nobody cares
Then do what I asked. What will it take to get you to block me?
Absolutely nothing because I have zero clues in who you are.
You and your opinions suck, so block me clown.
Instead of that I’ll just report your for harassment
Yeah and block me too.
How bored are you?
Very bored and very pissed off.