I'd say revesal is not just within reach, it's just a matter of people deciding to do it. We know that just digging a bunch of crescent-shaped pits/ponds is really effective at turning desert into green space, and that's hilariously low-tech.

Add on actually complex interventions and ngl i think it could be reversed within like a hundred years.
I mean imagine if massive desalination plants were built and the water pumped inland, we can do that shit, it's just expensive.