You don't need a crystal ball or a 1985 DeLorean to see where the future of digital marketing is headed. Just look at another one of your business areas for insight:
IT.
Remember when it was the norm to hire an IT person to be on staff and crawl under tables all day fixing printers, installing software and troubleshooting your fax line? While your IT person was too busy removing spyware on your machine, technology exploded with new servers, apps and services that the fully-utilized and time-strapped IT person knew little about. Physical and remote support through apps like LogMeIn, TeamViewer, Lync and GoToMeeting made supporting and pro-actively monitoring technology from anywhere a breeze. IT support costs decreased as the service got better. Most companies have rightfully done away with their in-house help desk. They still keep a technical person on staff, but mainly because that person knows the organization. They know Joe in accounting is always on his phone and would love the Freshbooks mobile app, they cringe at Martha in sales' sticky notes to remind them of calls and suggest a CRM. These technology all-rounders are the CIO now. Most businesses outsource the IT support function of their business to Managed Service Providers (MSPs). They are your company's IT guys. It's the MSP's job to support, grow and maintain your technology in a way that limits escalating IT costs. Training and providing technicians is on them. Not you. They have the people, technical knowledge and availability that one or two in-house technicians could never have.
The same phenomenon is happening in digital marketing. Your current "digital" person may be the one designing creative, managing search campaigns or coding apps now, but their role will need to change to something more results-based than task-based for them to survive. These individuals are valuable because they know how your business can benefit from various digital marketing initiatives based on their experience of i) already being on your team and ii) previously doing the digital work. These 'hybrids' can work with an agency or technology providers on making sure that your digital needs are met. The work itself will be done by digital marketing management agencies -- MSPs for your digital that can manage your websites, develop apps, SEO/PPC initiatives and creative design all under one roof.
The amount of digital avenues, tactics and tools available to support your business is exploding. You need to rely on hybrid marketing people that know your industry and digital well. Your in-house digital marketing director will make you the map and drive the car from point A to point B, but they won't build the DeLorean to get you there.
They'll leave that to Doc and Marty.