As I recall, your original claim was that it would be possible for 'any kid with a laptop' to effectively remove the 21M bitcoin cap. This is NOT an example of that happening.
After a hard fork, as long as both branches survive, there are twice as many bitcoins around. If you had 100 BTC before the fork, then after the fork you have 100 "Series A" BTC and 100 "Series B" BTC.
As I clearly said every time, whether people bother to mine and use each Series is a political and marketing qestion. There is no technical obstacle to both series of bitcoins surviving and retaining some value (but quite likely their combined total value will be no greater than what the "Series A" were worth before the fork).
At the last hard fork, everyone agreed to abandon the "Series A" bitcoins and use only the "Series B" ones. If we have another hard fork to increase the block size, some people seem to be willing stay on the "Series A" branch. I don't know what will happen, but, agan, it will be decided by political processes, not by technical mechanisms.
I am not sure, but i think you do not understand how the bitcoin network works. Every day we have several "hard forks" in the form of orphaned blocks. You simply do not understand the consensus mechanism, if you insist that A and B blockchains can coexists - with the same mining power behind them!- for more than say 2 consecutive blocks (on avg 20 minutes), and that they both individually represents bitcoin as per se. No, they do not.
The whole point of the consensus mechanism is to only and ever follow the longest chain of blocks in the long run, a.k.a. deciding which chain of blocks (A vs B) represents reality, and totally disregard transactions happened in the less long chain of blocks once a the n+1 block found. Hence your theoretical "B" chain would be instantly will be abandoned by the majority of miners (mining is automated by algorithm, not a press a button every ~10 min if you accept or not), resulting in that all the nodes will continue downloading and propagating the longer A chain, essentially destroying the B chain by the time the next block found. That B chain n-1 block became an orphaned block.
Yes, you can mine your own forked "B" copy of the blockchain at your laptop - offline! - until you start synchronise with the network, your B chain gets instantly overwritten by the majority A chain.
Also, your B chain will not ever propagate because: the moment you fork, you also inherit the difficulty of the A chain. That difficulty is so high, that your laptop will practically never finds the next block (which by the way will be without any transactions, since you are offline from the main A chain nodes), and without no new block, your offline node/mining copy will never reach enough blocks (aprx 2600) to reduce difficulty. This means that B chain will be hopelessly shorter than the A chain -> rejected by all miners/nodes on A chain.
TLDR.: Your idea will never work -not even in theory, since you missing the point in the first place- because the whole point of the PoW census is to have only ONE representation of the true about transactions (unspent BTCs sitting on addresses). By the way any full node wallet has the whole copy of the blockchain, every time you go offline more than 1 block, your copy is forked from A chain to B chain (n-1 long blockchain)....
EDIT: if you think that the state of the blockchain is a political decision, you are seriously should STOP posting bullshit here please. You do not understand the very basic idea: consensus through mathematical proof independent of central authority ( which is politics...)