Array of 4x7 Segment displays using demultiplexer. Need PNP transistors!
The top half of the diagram can go basically unchanged: except the resistors need to be lower to accommodate the Blue LED's different voltage.


  Given a transistor drop of 0.7V, and wanting a 20mA current through the LED, figure:
  5V-3V-0.7V=1.3V across the resistor, 1.3V=0.02 R, or R=65Ω.


The bottom left of the diagram would replace the bank of four resistors with both the demuxers (outputs 0-2 to A-C on both demuxers, and using output 3 as a chip-enable with ~G2A on one and G1 on the other), then put resistors on the sixteen outputs to the transistors.


  The resistors could probably stay at 10kΩ. Then again, @SperoPefhany in this answer suggests that no resistor is required at all...


The bottom right of the diagram would replace the NPN transistors with PNP, with their collectors connected to ground - and there'd be sixteen of them.


  Given @stevenvh recommended BC337, the PNP complement is BC327.