I currently ride a bike with a Nexus 8 hub and rim brakes.
Previously, I rode a bike with Nexus 7 hub, roller brake rear, and disk front. This combo worked really well, and if OP is swapping fork out anyway, definitely an option. Another option to keep the stock fork and pick up a front brake would be to go with a drum brake. Sturmey-Archer offers them, SRAM used to, when they were Sachs, no idea if they still do.
The Nexus hubs w/o brakes are fairly easy to remove once you learn a trick or two for undoing it and then rethreading the shifter cable at the rear. Hub brakes only complicate things, although disks should be pretty straight forward. With a coaster brake, you have to unbolt the torque arm on the left side; with a roller brake, you have to unbolt a torque arm and remove a cable.