They will soon run out of weapons and ammunition as no-one can or will supply them and they will be hemmed in by BD and China. China gets S Tibet in my possible solution which I know Indian Hindus will never accept, even if to permanently get rid of Muslims from their country.
If you do not accept my proposed solution just say so but saying the tribals have any chance in a full on war with BA is ridiculous.
No your first false assumption is india will abandon them.
Second assumption is the tribals(who are actually quite urbanized and ahoms and manipuris are an old civilization and culture)can't go berserk and massacre every miah in their states if they even have the slightest inkling of any threat to their homelands.
And finally the ever ominous mr amit shah is already on the problem.