What is the cause of cerebral palsy? Is there any hope on the horizon?

Some do beter. CP is a broad term applied to a disorder of movement & posture related to brain injury occurring at any time from pregnancy to the 3rd birthday. If the muscle control centers of the brain have been damaged, those cells are lost. Babies have some ability to re-wire some functions, so PT can help. Most improve some with age, some have major difficulties in life.
Brain injury. Cerebral palsy is caused by an injury to an immature brain. Typically it occurs in a child who is born prematurely, but can occur at any point during pregnancy up to the age of 3yo. It is a nonprogressive condition, but its impact on the body may change over time. Unfortunately there is still no cure. There are some preliminary studies on stem cell therapy, but not enough info yet to recommend.