Will the new algorithm make mining more profitable? That's the most important question for me
More profitable how? There are only 21 million coins to mine. Make mining more efficient maybe? But what's more efficient than ASICs?
ASICs mean a more centralized world of BTC where a few manufacturers and a few pools control all the income. What is so great about that? Satoshi designed it so anyone could mine and anyone could earn BTC.
I don't know what Satoshi designed it to be, but he didn't expect "mining" to be a specialized industry. Maybe if he did, he would be embracing it. ASIC-resistance, or the path to more efficiency of work, would be pointless.
Well, let's say some mining pool has taken over 51% of the network and can now manage your state as it wants, for example, change the chain that you have 0 coins, what do you say?
pools cant change the main rules.
they would get their blocks rejected. they can only choose what transactions get included or excluded.
Yes! By the non-mining full nodes validating everything in the network.
thirdprize, full nodes order blocks from the miners, if they're invalid, they will be rejected. All the miner's work will then be wasted.