。。
She might be late. In that case, I'll wait.
Literal
Late come [might-かもしれません]. That case [topic-は] will-wait.
Two sentences joined thematically. 遅れてくる ('to come late') uses ~てくる for directional movement toward the speaker. かもしれません is the polite form of かもしれない. 其の場合は ('in that case') uses the formal kanji 其の for その — unusual in modern writing, giving it an old-fashioned feel. The second sentence shows a conditional response to the first.