Your post reminded me of this early 2020 (pre-COVID) article about Huntsville's long-term walkability goals. Quote at the very end:

City leaders say that they have a 20-year plan and vision focusing on walkability. They want to make it possible for you to walk more than 17 miles, from Alabama A&M to Ditto Landing using sidewalks, crosswalks, and greenways, without jaywalking.

I wonder if the "greenways" they supposedly worked into their plan take advantage of at least some of the space carved out by the HMCRR tracks. Or if they envisioned an entirely new route. Either way, I won't hold my breath for it.