Honestly, any decent handset that will allow running Mer based OS would be good. While having a keyboard is a bug plus, I care more that it should have an sd card slot, allowing booting alternative Mer based OSes (like Nemo) easier without wiping the default Jolla OS. And preferably CPU/GPU specs should be higher than N9's ones. Ah, and also having a wide choice of frequencies (inlcuding LTE ones), since if it'll be narrow - it won't be usable with various providers.