Are we sure that all Bitcoins will one day be mined? If the costs of mining are rising, the interest in mining may decline; and despite the value of BTC at this time, people may lose interest?
if interest in mining decline, home miners and team miners leave the blocks, system will be easier but miner companies will begin to mining more seriously than before. Im talking about big companies. They spend money about 100M+ so all Btc will be mined one day.