Is there a plan to have abook for Joomla 3.X? YES :-)
Will Abook for Joomla 3.X be available soon? Ehm, we hope :-/
Federica is working to complete migration rewriting of code to allow Abook working on Joomla 3.X.
Abook aim to be a well-written code (shhh! don't tell this to Federica or she blame me!), but writing a code that follow all rules of the Joomla Framework isn't a very simple trip.