Please make this happen. On paper it seems possible because the vast majority of Tswana speakers actually live outside Botswana.
Two ways to take this:
Simpler: Can Britain somehow secure a larger territory for the Bechuanaland Protectorate?
Insane (post 1900): Botswana somehow annexes Bophuthatswana or a similar construct (or vice-versa, with the resulting entity taking the Botswana name). Probably at gunpoint.
What are the odds for each? And in either case, what would be the repercussions?