And introducing a blockchain to the equation changes nothing about that! It doesn't magically make applications interoperate with each other, or make them consume each other's data, or force them to maintain API compatibility. At most, it provides a shared, public location for them to store data -- and even that has some very awkward limitations associated with it.

A lot of the blockchain boosterism I see online comes from a place of assuming that the blockchain represents a solution to a problem, and trying to work backwards from there. Avoid that.