It is not a wishful thinking. I favor that India, Pakistan and Bangladesh should try to unite and regain to be the one we knew as India. We need to undo what we did years back.
Given the events and shapes Pakistan and Bangladesh have shown in last many decades, this unification effort may seem to be a dangerous plunge to many. In fact the most vocal critics of this idea say that we do not want to inherit the problems Pakistan and Bangladesh have created in last many decades, i.e., their pointer is towards growing extremism and fundamentalism. They often say that any efforts towards unification with these two Islamic countries means inheriting the ‘hell’ they have created in the name of religion. Herein lies the solution itself: India did not go that way because we chose to be a secular polity and not a theistic state! We chose plurality, tolerance as our guiding principles and that is why the monster of fundamentalism and extremism has not been able to raise its head in India to that extent that our survival could be at stake!
Thus any talk for unification must include embracing the basic constitutional framework of a secular polity: secular constitution as our lynch pin!

I do not see why the countries of Indian sub-continent can not come together to form a bigger India. Let the estranged brothers come together! We have so much in common, and the differences of religion can be overcome by implementing the governance based on modern laws of land and not by religion. Well, we are already spending so much money on guarding our boundaries against each other, much lesser money will be required to maintain ‘communal harmony’ if people are afraid of the communal monster! Religion is a real serious impediment towards the idea of unification of these 3 nations, but it is possible to overcome the differences if we rise above the occasion! This needs statesmen and not petty political approach as we see by our modern leaders of the three countries! We need statesmen to come forward and carry this idea to a meaningful conclusion!
The advantages gained by unification are: 1. Bigger land area, thus netting more natural resources 2. Lesser money required to spend on defense and moreover, and 3. It will be a natural culmination of efforts to regain the lost boundaries which were divided -as we often like to say- by not us but by erstwhile powers (Britain)!