Good job man. Great day indeed

Strange, my mother in-law bought some yesterday after 7 years of badgering. 😆... Something is happening.

The miners can choose to start a chain that would increase the overall supply, however it dilutes their holdings so they are not incentivized to increase coin amount.

Increase in supply is an hard fork, a change in the rules that is not compatible with the current ones, so when you hard fork you are basically creating a new coin with new rules and you need almost everyone to accept that this new coin is still the real one, a majority of miners would have to agree, and most nodes would have to agree also.

The network doesn't actually need all of these miners. It's okay if they shut down.

to change the consensus in a successfully way (ie: without risking that your fork goes to 0) you don't need the majority of users, you need the majority of the economic power. Let's say that within that date the govs manage to get 80% of the supply (via ETF or by law-enforced custody of user funds or simply because users keep their stack on exchanges). In that case they can successfully change the supply

When the subsidy ends, mining still continues.

Even without transaction fees, or even transactions, there is incentive for mining to continue. Satoshi's million coins is Satoshi's alone and will not be claimed by the system. In the code, the subsidy gradually drops to zero and then there is no more new coins generated. Existing coins would still be spent and block production would continue.

For the supply to increase you'd need an economic majority to indicate support, then apply a hard fork, and hope for the best. I very much doubt this would be achieved. Game theory alone makes it improbable and a success on it would be indicative that future inflation would happen over and over negating a key reason to use it.