I don't think an alternate timeline presented in HotS to give a vague explanation of a costume for a character should be used as any sort of justification to introduce Dryads and Keepers. Aside from a couple of technical issues, I just don't see them picking sides. Yes they are closely aligned with the Kaldorei, but they protect and preserve nature. That has put them into conflict with the Horde in the past, but the Cenarion Circle has taken on a very neutral role in recent years.