The first is that phased arrays are an enabler for satellite based internet access.
Earlier this year, Elon Musk announced the development a network of satellites that will provide worldwide internet access. The system will require the use of phased array communication receivers since the satellites are low earth orbital, also called LEO satellites, rather than geostationary — like DirecTV. The estimate is that they will need approximately 50 million phased arrays. If each phased array cost $250 each, this translates into $12.5B in phased array radar sales to SpaceX customers alone.
The second reason you need to know about phased arrays is they are an Internet of Things enabler.
IoT solutions will use phased arrays for the millimeter-wave connections. This is true for consumer electronics components such as mobile phones, and televisions.
The third reason is that back haul systems will need to use phased arrays.
A large portion of phone calls and internet data transfers use the wireless back haul system. As these systems migrate to millimeter-wave and terahertz frequencies, they will need to use phased arrays to keep their antenna beams locked.
The fourth reason is the US military is migrating many of its passive radars to active radars.
The old systems that used passive radar arrays are being redesigned into active radars. This is being done to so that the US will be ready for growing military threats from North Korea and China.
Wrapping It Up
The bottom line is that phased arrays provide performance and functionality that just cannot be achieved with other methods. Over the next several years, the market for phased arrays will expand beyond military systems and into consumer and infrastructure systems. Shameless plug: MPT provides solutions for satellite and military based phased array systems.
 R. Sturdivant, M. Harris, Transmit Receive Modules for Communication and Radar Systems (Norwood, MA: Artech House, 2015)