Check 21 is the new electronic check clearing system. In the near future banks will be able to scan checks into their system and transmit them electronically thereby eliminating the need of using priority air couriers.
Ameriflight, founded by transporting checks has recongnized this technology and is now diversifying into other field of service to maintain profitability.
I wouldn't worry about it too much, those time building jobs will still be there for you. You'll just be transporting other things.