California’s schools are bracing for a dramatic exodus — with the state expected to lose almost a million students over a decade-long period as families flee soaring costs. Federal data shows enrollment in the state’s public schools will plummet 15.7% by 2031, hollowing out classrooms in a system that currently serves about 5.9 million.   California’s public schools are bracing for a dramatic exodus, with almost a million students poised to leave classrooms as families flee the state’s soaring costs. Getty Images The decline is nearly three times worse than the national average, which is projected to drop 5.5% by 2031. And while 40 states and Washington, D.C. are expected to lose students, California classrooms are shrinking faster than any other large state.   A mix of skyrocketing housing prices and eroding school quality is pushing families to seek better lives outside the Golden State, according to a report from the civic group Garry’s List . Even though 40 states and Washington, D.C.…