A bright future means that the future is as beautiful as a brilliant career. This word is mostly used for blessing.
You can bless the leader like this: sometimes, you will make great achievements one day, and your efforts will be rewarded. The future is bright and the day of promotion has finally come. I wish the leaders a prosperous career, and I also wish the leaders good luck, constant happiness, all the best, and step by step promotion in the new year.