Passenger or cargo planes without pilots will never exist.
The former I can understand arguing for, with the human element in the loop and the invaluability of human life, your statement may hold true for a long time. The question is, at what point will it become acceptable to stop referring to that human element as "pilot" in exchange for say, air vehicle operator, with suitably adjusted requirements for training and maintenance? Runway to runway automatic flight capability had been demonstrated a long time ago and many times over and all the initial speculation surrounding the Asiana prang makes a certain statement with respect to the respective "pilots" aptitude. The argument that "had the ILS been operational and the pilots' hands tied, the accident would have been avoided" will be heard in the upcoming lawsuits. From there it is again one step closer to de-labeling the human operator as "pilot" in favour of a yet more automation oriented role, since it was once again demonstrated that the respective human element has failed in its ultimate role to take over for failing automation.
Now, pilotless cargo planes? Ten years tops. A consortium centered around BAE Systems is vying for unmanned aircraft to be granted access to common civil (in their speak 'non-segregated') airspace and have recently executed a successful flight trial, see
here. Once that access is granted, it is only a matter of finding the right balance between the value of your cargo in transit, the cost of transportation against the risk-hazard scenario at hand (potential liability and the probability of an accident). Insurance to cover such will be available from day one, for adequate premiums of course. Notwithstanding that there is a myriad of unsolved questions surrounding the prospective commercial operation of unmanned aircraft and some will quite possibly have to be resolved in courts.
So in order to sum it up, my half interested and somewhat educated yet by no means expert guess says that in foreseeable future we will see pilotless freighters - or more precisely, piloted from the ground - while passenger traffic will retain manned pilots. Their role will however continue to evolve towards yet more focus on automation and become somewhat more that of system operators rather than seat of your pants aviators.