The way I see it
1. Its Vision. That means Wakanda and the heroes can repel this invasion, and then either T'challa tells them "you cannot stay here" and tells them to go, or Shuri is able to get the gem out and then T'challa tells them to GTFO. Either way... Wakanda still stands, the invasion was pushed out, and the plot moves on to Mind stone keep away
2. if it is the soul stone in Wakanda... Thanos has to come and Wakanda burns. T'challa isn't going to send away a stone they have had for centuries. They will push back this invasion but THanos will come next with a half completed gauntlet and burn it to the ground to get it. There is no long term victory in this scenario.
so I think i'd rather it just be Vision TBH.