PM Modi[[1]] (arrive) via sea route in Sri Lanka to discuss about the economic condition of Sri Lanka.

explanation – in future continuous tense we use Will/shall + be + v1+ing, as we know will and shall represent the probable action for the future time and they also are modals. So, with modal we use base form of the verb so we use ‘Be’ with will and shall and to make it continuous we use V1+ing. Therefore, Will be arriving.