So without getting overly technical let's just say the code in the new wallet is able to take a look and see the version of a node trying to connect to our network and it can decide that version is not the proper current version and then reject it. All of this is done automatically. So if a wallet is not upgraded at the time of this fork block 25000 then that wallet will not be able to connect to our network of nodes any longer. Banned, kicked off, evicted are some words that come to mind. The reason this is necessary is to prevent someone from gaming the system by running the previous version and taking advantage of the incorrect/inflated interest rates.
In terms of what happens to those shiny new coins. That is a bit of a situation to say. So picture this in your mind and get a visual: we had a blockchain running only one running mind you so picture this horizontal line.... then exactly at the fork - that horizontal line splits into 2 and now you have two parallel horizontal lines after the fork. You know essentially 2 parallel blockchains running side by side. They both exist and they both contain the same coins that existed prior to the fork.
Now going forward past that fork these 2 different parallel chains are not interchangeable. One chain can't send coins to the other chain and vise verse. They are literally two different animals. So past the fork coins mined on chain 1 are only good on chain 1. Coins mined on chain 2 are only good on chain 2. If you are on the old version after the fork and mine coins those coins will be rejected by the new version. But, both chains do exist and both chains do have coins and both chains can move forward and continue to live.
A great example of this was when Bitcoin forked into Bitcoin Cash. I had a bitcoin wallet running and I had a bitcoin cash wallet running before the fork. After the fork I got free coins. The same amount of bitcoins i had before the fork i then had in my bitcoin cash wallet after the fork. The coins doubled and the new free batch of coins is on the BitcoinCash fork. After this fork the same coins exist on both chains and yet the coins cannot pass back and forth but are stuck on one of the 2 chains.
If this is not clear let me know what questions you might have.
So if i'm one of these 80 odd people still connected to the pool, and if the pool is using the old daemon which is generating the old version of the blockchain. What happens to those 80 odd people. All of them will get banned? Does this ban last forever, or would it be possible to revert back to a previous point, and resync back to the new blockchain?
If your wallet is up to date everything is fine for you and your coins in your wallet. But IF the pool really uses old version, the pool would not be able to send you coins (old version) to your wallet (new version).