Author here. Yes you are reading this incorrectly. Look at the contingency table.
objective c to swift: 5216 swift to objective c: 1639
(sorry about the small font size though. had to squint really hard)
objective c to swift: 5216 swift to objective c: 1639
(sorry about the small font size though. had to squint really hard)
The future probability table shows that Swift is to the left of (smaller future probability) of Objective C. The coloring of the chart shows a much darker square for Swift -> Objective C than for Objective C -> Swift.
It seems surprising given your contingency table that your analysis would show that Objective C is going to be the more popular of the two.