In my opinion, I would remove the entire spike with the flowers and buds on it. I would concentrate all my energies into allowing the mother plant to give all it's strength to growing the one baby Phal. I don't think it would be in the plant's or your best interest to get too greedy here.

Whether you decide to grow your Phals mounted or potted, base the decision on your observations of which method brings you the most success.

Seems a little premature to write this thing off just because it has a yellow leaf. Leaf death is a regular activity. It doesn't necessarily mean that the plant isn't healthy. Growing a keiki is not a sign of disaster either, it's a normal thing.

If you have keiki and you want to retain it, then just let it grow. Sometimes we make this stuff too complicated. I wonder who tacked down keiki's in the wild?

I was also wondering if the 2 leaves that are yellowing are the only 2 leaves or are there more healthy ones on the plant? I couldn't tell for sure in your original post. That would tell a lot. :)

Thanks again for everyone's help.

Yes the leaves that are yellowing are the only two leaves on the plant, and they are getting yellower day by day.
So I think this plant, for whatever reason, has reached the end of its lifespan. I will "rescue" the keiki as you all suggested, cut off the other spike w/the flowers, and then speak kindly to it andperhaps it will ressurect itself.