The expulsion of the Acadians occurred only as a result of a very confused situation in the Maritimes, with France and Britain actively contending for control of the region and Acadians scattered on both sides of this frontier. The subsequent ethnic cleansing in the Seven Years War was probably expected.
If Acadia had been united under France, the colony then falling to Britain in 1757, then I don't expect that there would have been an ethnic cleansing. What would have been the point in deporting a population that, from the British perspective, had not demonstrated its lack of loyalty to Britain over the previous forty-odd years? I suppose there's the possibility of acquiring lebensraum on the fertile drained lands of the Bay of Fundy, but the New England Planters' migration to the old Acadian lands was a consequence of their previous inhabitants' expulsion, not a cause.
Assuming that New France falls, I'd think it quite likely that the colonies of Acadia and Canada would share similar fate, with Britain extending religious toleration to the colonies' French Catholic majorities and allowing a certain restoration of the older political and economic orders under British rule. One complicating factor that I could see would be the relative attractiveness of Acadia to settlers from New England and elsewhere. The Bay of Fundy area would remain the centre of Acadian civilization, but the rest of Acadia would be largely unsettled. It would be open to settlement, being much more accessible than (say) the future Ontario. What sort of arrangement will apply here?