I work for an IBM business partner and this reply is based on my best understanding of the current LotusLive Notes feature set. It's not an official IBM answer.
If you choose the LotusLive Notes Hybrid approach, where you retain some servers on your premises (maybe just two), then you can replicate your choice of directories into the LotusLive Notes environment. This could be one directory or many, and it could include extended directories catalogs that have entries merged from various component directories.
If you choose the LotusLive Notes Hosted-only approach, you cannot currently integrate any external directories.