When all 21 million Bitcoins have been mined in 2140, mining rewards will cease, and the only source of income for miners will be transaction fees, which are expected to incentivize miners to continue securing the network.
The impact on the price of BTC when mining stops would depend on the supply-demand dynamics at that point in time. With a fixed supply and potential demand, the scarcity of
BTC could potentially increase its value, but it ultimately depends on the overall adoption and usage of BTC in the future.