What to do with a result too small to be publishable, but interesting nonetheless? Let's assume, for the sake of example, that I have found a new figure of merit which is of the same complexity as the one currently used, but is much more justified from a mathematical and physical standpoint. However, the whole development barely goes over one paragraph (maybe two), as the "proof" is extremely simple and straightforward.

Now, I was planning on saving this smaller result for a bigger paper on the same topic, where I'd introduce this new figure of merit along with other results, but the future of this other paper has become quite uncertain lately.

Is there any way I could still present this new (small) result?
You can think of publishing it as a short communication, many journals accept this kind of contribution (they can be designated in different ways, depending on the journal). As I recall, the shortest article ever published was of about 3 lines [1] ;-)

[1] F. Lenz, "The Ratio of Proton and Electron Masses", Phys. Rev. 82, 554, 1951.