Neither people or technology are the root cause of the difficulties in sharing intelligence. Politics is. Government agencies all want to contribute to stopping terrorist attacks, but bring to the table different specific skills and priorities. These differences can make them reluctant to share intelligence with their counterparts. Some fear that their counterparts will reveal methods of intelligence collection that need to be kept secret or will expose information that the terrorist can use to plan their next attack. Others are reluctant to share intelligence that casts a shadow on their efforts or undermines their skills and priorities. On the flip side, some agencies are unwilling to make decisions based on information they did not collect and cannot themselves verify.
This is politics. Replacing officials and improving technology will not make it go away. It is not clear what can. The Director of National Intelligence does not have much power to force or entice agencies to share more effectively, and the president may be distracted by other issues or hobbled by opposition from Congress.
One solution might be to foster an intelligence culture that rewards sharing. The military has had some success in promoting inter-service cooperation by, for example, rewarding officers that serve in other areas of the military or government. But this is not an overnight cure. At best, it might create a culture of greater sharing in the next generation of intelligence professionals. Politics can be tamed, but it won't go away.