1. Transaction fees would instantly go up, to accommodate the lack of block rewards being a thing and transactions would likely become a lot more expensive consistently.
Eliminating the subsidy does not affect supply or demand of block space, so how can it affect the price?
2. The coin would die, or be dead before it's fully mined out - this is my personal prediction for Bitcoin, don't think it'll survive enough for every last coin to be mined out.
The evidence contradicts you. The subsidy has been halved twice now, and rather than Bitcoin approaching death as the subsidy approaches 0, Bitcoin is growing. Also, there are coins that have no subsidy and are mined just for fees, and while they may ultimately die, it won't be because they have no subsidy.
3. It would only be available for purchases on exchanges and P2P, with there being no supply, demand and the price would instantly rock up causing the coin to be instantly worth a lot more.
You are confusing "production" with "supply". Even if no more coins are mined, there will still be a supply. There will always be people who are willing to sell their bitcoins -- that's the definition of supply.
Furthermore, demand (and price) would not "instantly rock up". Scarcity does not affect demand. People won't want to buy
more bitcoins just because they are no longer produced.