The airline integration won't happen for a while - perhaps even early 2016.
In the meantime, codeshares mean potential savings, and potential problems with regard to standby, rerouting, irregular operations and whether or not reroutings to other airlines can be made, etc.
IMO it's about risk tolerance until all the relevant issues are unified. For me, that means avoiding AA / US codeshares like bad seafood.
http://www.flyertalk.com/forum/ameri...solidated.html