~KEIKI~
 

Well I learned some about these baby attachments here, but this one is a mini dendrobium or in it's seedling state & seemed to be doing fine until I gave a tug to the main mother stem and it pulled right out.
Uncertain exactly where to go from here as the roots on the baby are far too small for transplanting. I have just been leaving it be for now.

The keiki probably got started because the cane was dying. It has been feeding off that old cane (which hasn't been doing anything except passively feeding the keiki... it looks like it has been rootless for awhile)

What I'd do is leave the keiki attached, and pot the whole thing in a pot just wide enough for the old cane lying horizontally so that you can partiallly bury the roots of the keiki in the medium. (You could trim the brown, dead bottom part of the cane to let it fit into a smaller pot, there's still some "juice" in the upper part) If you have a shallow pot (like a bulb pan) so that you don't have to trim the old cane, that would be even better. But that will give the keiki a chance to root in the medium, which it likely will do before it has totally sucked the old cane dry.

IMHO, you could separate and pot it. I think I'd just put it in moss and lightly tent it. That's not a bad amount of roots.

I think my question would be why the parent rotted off?

Keep it warm over winter for best results.

Like this?:

Looks great!