Boston Ballet, searching desperately for a new home for its annual production of The Nutcracker since being kicked out of the Wang Center in favor of a touring Radio City Christmas show, may have found more than just a holiday staging ground. If things go the company’s way, the city’s Hynes Convention Center could be renovated into a performing arts center, and Boston Ballet could take up permanent residence there. Of course, the company doesn’t own Hynes, and hasn’t yet spoken to the city of Boston about the plan, and any renovation would take years to complete, but what the heck? It never hurts to dream.