All you have to do to keep sideloading is
roll back to 1.4.0,
root,
replace the device manager, stopping future OTA updates.
I'm not exactly thrilled with B&N either, and the prospects for things like CM, USB host and even microphone access are in doubt -- as well, those of us who cling to 1.4.0 will miss out on bug fixes, but this is a very good tab at a very nice price. Some folks focus on the storage and sd card advantage on Fire v. NT, but the killer spec is the ram. A year from now, I'm not going to feel a memory pinch. I'd be less certain with half the RAM.
If USB host (read: keyboard) makes the cut down the road, I'll feel pretty happy. Vote for it at the B&N forums
here.