There are 9 flights/day MIA-MCO, so when you misconnect, you will be rebooked onto the next available flight. If you don't want that, you can simply have the segment cancelled.

But, and this is important, if you for any reason cancel the MIA-MCO segment, do not count on AA to preserve the remainder of the ticket. Check after the segment is cancelled to make certain that the onward/return are still active.

As others advise, whatever you do, don't simply no show for the MIA-MCO unless it is your final segment.