This has actually already happened with Monero. The mining reward schedule was much more aggressive in it's diminishing returns. Once the mining returns cross a threshold of not being able to sustain the cost of mining things dried up very quickly. Devs jumped in and added Tail Emission [1] so that all blocks have a fixed reward of 0.6 XMR that will never change or go away.
[1]: https://www.getmonero.org/resources/moneropedia/tail-emissio...
We found out with previous Bitcoin forks, how influential companies and miners are. 21M is non negotiable, and which stakeholder would want to dilute themselves?
When it comes to miner prerogatives the day is never done, they are the sole arbiters of what "winning chain" means, and when they are incentivized to act in unison their will is indomitable.
> and which stakeholder would want to dilute themselves
Miners. Based on your definition, "stakeholders are diluted" every time miners make money, so if the choice is between continuing to make money or not, it's pretty obvious what decision they will make.
I suppose there's a possible future where the miners do nothing and bitcoin transaction fees skyrocket in response. At that point I would expect a mass exodus to altcoins with cheaper transaction fees, but I don't see the miners acquiescing to this future.
Bitcoin has the same problem, and cryptocoin enthusiasts are fooling themselves if they think that miners won't raise the 21m cap when the end of Bitcoin rewards start looming.