The struggles of ballet companies across the country are well-documented, but you’ll pardon the Boston Ballet for feeling specially cursed this year. Last night, the curtain fell on the company’s last performance of the Nutcracker for 2003, and possibly forever. Having been informed that the Wang Theatre, the company’s Nutcracker home for 35 years, would be replacing the classic ballet with a traveling show next December, Boston Ballet is desperately searching for a new home in a city famously lacking in performance space. With Nutcracker typically bringing in as much as 50%-60% of a ballet company’s annual revenues, no one even wants to think of what could happen if Boston Ballet can’t mount the holiday show.