Difficult to say.
Most Muslims won't mind being part of Bangladesh. But I think we are more conservative than most Bangladeshi tourists who come to Kolkata. We never visit temples for instance. BD tourists often do. May be because only the rich come. I don't know. Bolte parbo na.
Almost no Hindu will like to live in Bangladesh. There are few exceptions. Most would just simply pack their bags and leave to Hindu majority areas of India for safety. Asansole jemon holo.
Shame as the Hindus would get far better opportunities in BD than they are getting in India.
A greater BD would mean that Hindus make up around 30-35% of the population and so would hold real power in the country. In India they count for nothing in front of states like Maharastra and Utter Pradesh.
They have nothing to fear in BD to be honest as BD Muslims are very tolerant.
I do not blame them for wanting to be with their own religious group but they would be economically better off with BD.