I do not see any big friendship between IN and BD, precisely due to religious reasons. Every other post started by Indian members here always reference the "historic, barbaric, disgusting, violent" invasion by Central Asian thugs, who "forced" Islam (which is actually another word for Arabic culture) on the otherwise peaceful people in BD (which was otherwise had the "ancient Indian culture"). That is easily disproven and a stupid propaganda statement. However, since Indians will not give up making such statements I cannot see how they expect to be "friends" with Bangladeshis, who, even though we are not extremists, are proud of our Islamic identity. You cannot openly make anti-Islamic comments every other post and expect to accepted as friends by BDeshis.
And aside from that, there are millions of other Muslims, Iranians, Lebanese, Pakistani, Arabs, etc, who are very friendly to Bangladeshis precisely due to the shared Islamic identity. This acts as a "pull" factor, and the Indian curses act as a "push" factor, for BD to have better relations with the Islamic countries.
In the future BD-IN relations may be "good" (meaning the absence of any hostilities) , but Bangladeshis and Indians will never love each other. Then again, according to Indians there is no such thing as "brotherhood" and every country must look after its own interests only, in that case, relations would be like this anyway, if BD was also a secular country. So, in the end, nobody loses anything, except Islamic countries have better relations with each other. Which is the best thing that could happen, from our POV.