Funding will remain a constant challenge for UAVs, but it's not the only one.
Over the next quarter century, UAVs will need to become more efficient to operate. Currently, it's one-man-to-one-machine, meaning each aircraft requires the constant attention of one person. That ratio has to improve.
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"We're there now," said Insitu's Ryan Hartman. His company is testing a version of the Blackjack that will let one operator control four UAVs at once. Also, teaming UAVs with pilots to fly "manned-unmanned" is a program being tested with the P-8 Poseidon and V-22 Osprey.
The industry is also dealing with how to use UAVs for lethal purposes. Arming drones will continue, experts say. The question is how much autonomy these unmanned aircraft will be given.
Could they ever decide on their own to kill?
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"There are some decisions that humans make that make the doctrine of war work," said Hartman, "and so I think that's a very low probability."
He and others believe that despite backlash and concerns, UAVs have proven themselves too valuable to dismiss. There very well could be more unmanned than manned military aircraft in 25 years, and that's not even counting the potential for building them to fly across the U.S.
"The weakness has really been the reliability of the systems themselves," Hartman admitted. "Everybody in the unmanned systems industry recognizes the importance that reliability is what will enable us to provide capability in the civilian market and operate in the national airspace."
—By CNBC's Jane Wells.