It seems you are responding well to Entecavir. I think it is too dramatic for a doctor to say you have to take this medication for life. This assumes that science will stand still and that no progress in a cure or treatment for HBV will be made.
At the moments, some guidelines have rules to determine when medication can be stopped. The success rates are about 30%, but these rules are being refined as more biomarkers such as serum HBsAg quantity are being discovered and measured. There are also combination treatments with Interferon and other immuno therapies such as therapeutic vaccine, being developed that will lead to higher cure rates.
So take the medication, let your liver recover, stop the disease from progressing, then wait and see. Very few things are for life.