Hello,
In your opinion, which changes will occur in the Bitcoin Market once the last bitcoin is mined ?
Will the price increase because of rarity ?
Will fees skyrocket in order to pay for miners ?
Will the number of miners decrease, resulting in lower security ?
No because by the time the last one is made (in 2140) the rate of production would have slowed down so much that you wouldn't even notice more bitcoins were still being made.
Bitcoin production follows a logarithmic curve, where most are produced in the first few years, rapidly decelerating production overtime slowing down to a crawl. This is also going to stabilize its price overtime, against "stable" things like gold, not fiat which is intentionally devalued by governments over time.
This curve also happens to match its price rise against the same "stable" things. We may have perhaps seen the most gains in bitcoin's lifetime, while it will keep going up, it will slow down more and more until it goes slightly up against "stable things" (like gold) in the next century or so.
The number of miners will decrease (following the same curve) but it won't result in lower security. It still costs to mine, and this cost is going up (following the same curve). Actually fees won't be affected, and because of offchain solutions like LN, might go flat under 1 sat/B (which i use right now).