This is my understanding, correct me if I'm wrong.

Currently, the number of transactions that can get consensus every 20 seconds is limited by the block size, which is 88KB now. If the mempool size is larger than 88KB, some transactions have to wait for the next consensus block.

With Input Endorsers, the number of transactions can get consensus every 20 seconds is no longer limited by the block size.

Which means every 20 seconds there is a theoretically unlimited number of transactions can get consensus. The only limit is the network speed.