For a toddler with development delay, e.g., speech, comprehension, can that child ever catch up with normal contemporary peers? if so, how?

Maybe/not: Each case is an individual expression of factors often never known. It can be related to brain injury in the womb by poor blood flow, infection or metabolic issues. It can be a genetic issue. Therapy in an early childhood treatment center can maximize the improvement. However, you never know the end of this story until you read the book. You don't get to skip to the end.