You could go both ways; they knew that for a fact. The obvious implication—which neither Roger nor her mother had mentioned, so perhaps they hadn’t seen it—was that one could go into the future from a starting point, rather than only into the past and back. So perhaps if someone traveled to the past and died there, as Geillis Duncan and Otter-Tooth had both demonstrably done … perhaps that must be balanced by someone traveling to the future and dying there?
Foreshadowing a resolution to the shady Scottish peeper of book one/episode one? And Jamie’s dream/“sight” of Claire’s time revealed in this book?