Well the ADB predicts that BD will grow around 1% a year less than India over the long term. This fiscal Bangladesh should achive around 7% as opposed to India's 8.5%. This is worrying for BD as the already substantial gap in GDP/capita(india has 3,400 as opposed to BD's 1,700 at GDP/capita US PPP) will then grow larger still. The ADB projects that Indian's will be nearly three times as rich as Bangladeshis by 2050.
I personally think that Bangladesh is actually likely to grow quicker than India over the long term as Bangladesh should be able to model itself on the faster growing Indian states and will not be hampered by the slow moving, somes almost gridlocked, decision making processed that the federal Indian state is stuck with. Let's see what happens over this decade as if Bangladesh cannot grow quicker than India(BD government plans around 10% GDP growth by 2017) by the end of this decade, then India could just leave Bangladesh far behind