We now need an aircraft carrier to effectively counter Indian Sukhois based in A-N Islands and breach a naval blockade. Bangladeshi would be kicking Burma's a$$ today if we had possession of the Island.
First of all, our access to high seas(international water) is not dependent on using Indian or Burmese water because our maritime boundary has direct access to the international water. So, if India or Myanmar for any reason ban entering our ships in their water, we will not have any problem accessing global maritime trade.
Secondly, naval blockade is an act of war. So it does not happen unless two country goes to war. India can not blockade Bangladesh at whims. And Indian scope of blockading Bangladesh would be even less tenable if China or USA maintain strong presence in Bay of Bengal and Bangladesh maintain close co-operation with that power.
Thirdly, effect of Naval blockade is not immediate. It take at least a few months to feel the heat of the blockade if the blockaded country is self sufficient in food and fuel. We are largely self sufficient in major food items and if we create a strategic reserve of petroleum for at least 4-6 months, we can cope with any blockade until a cease fire is agreed upon. Our most of energy still comes from domestic gas. So, with our robust agriculture, domestic gas and reserved petroleum stock, it would be many months before we feel the real heat of blockade.
Fourthly, we do not need aircraft carrier to break any hypothetical blockade. A strong Submarine fleet with cruise missile, torpedo would take care of Sukhoi and other blockading surface ships and submarine. We are marching in this direction. What do think about our 1.2 billion dollar Submarine base in Pekua, Cox's Bazar? Just to shelter our two Ming class Submarine? This Submarine base will be able to shelter dozens of Submarine. Our full-fledged Naval base in Rabnabad, Patuakhali will also act as a Submarine base. So we are looking at a much stronger Submarine force in BN in the future.