We will hit the 21 mil cap way before 2033. The difficulty is set to make a block every 10 min, but as it is not adjusted every block, we will mine some blocks faster than 10 min and will hit cap before 2033.
You got the year wrong. The bitcoin block subsidy will continue to exist until approximately 2140 (not 2033).
Of course, if difficulty rises too much, or the exchange rate drops too much, some miners will shut off their equipment. Then blocks will average more than 10 minutes each until the next adjustment. It is really difficult to predict how that will play out in the future.
