With a cartridge BB if the shell threads are aligned on the same axis can the cartridge be unthreaded drive side with NDS cup in place?

Yes. I've never seen a NDS side piece that locks into the cartridge.

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I think you're seeing the cartridge as one part - looking something like this:

But remember its in TWO pieces - the main body that threads in from the drive side, and a much smaller supporting ring with a slight taper on the inside to support the Non-drive side.

The pictured unit should unscrew out the drive side once you remove the crank and spider and chainrings. In an extreme case you might be able to reach around with sliding pliers and slowly back the whole thing out, but that would be no fun at all.

Upshot

• There are no two threads that have to align.
• Even if they did, ones a left hand thread and the other's a right hand thread in 99% of bottom brackets (french and italian BB threadings are weird)
• The NDS spacer generally has a lip that would stop it threading in too far, there's no good way to wind that all the way through the BB
• And most threaded BB shells are slightly smaller in-between the threads, because that's the metal into which the threads were cut. That is, the crest of the threads is no-higher than the metal from which it was cut.

Most cartridge BBs have a shoulder on the drive side, which is also the side that's integral to the bearings and spindle, plus a non-shouldered left cup. Some are the opposite, and some have no shoulders. Some have two similar cups, one of which may or may not be shouldered, and then the bearing and spindle unit is a third piece.

Drive vs non-drive side is unimportant to the question you're asking. Shouldered vs non-shouldered is though. What's important is that when you're done, it's all properly torqued against each other. If there's a shouldered side, that needs to be torqued against the frame, and the non-shouldered side needs to be torqued against the main BB unit.

If what you're asking is if on a common BB with a shoulder on the drive side and the bearings and spindle integral to that piece, and an unshouldered left cup, whether you can leave the left cup untouched when you take the the main unit out, no, that's not really ideal. Unscrewing the drive side in that situation can easily rotate the NDS side out a little, such that when you reinstall the DS, proper contact with the NDS cup isn't made. Or, if it doesn't move at all, the ways things settle could cause you to be torqueing the BB against the left cup and not the shoulder against the shell. The better practice would be take out the DS, unscrew the NDS a turn, torque the DS back into the frame, then torque the NDS down properly against the DS.