If you have the conditions right, in my experience, the leaf will do one of three things within a few weeks.
1. The leaf will rot to mush. If this is going to happen, it usually happens within hours. Most often this happens if the leaf is kept too moist.
2. The leaf will shrivel up and become a dead dried flake. This usually happens if the leaf is kept too dry.
3. The leaf will persist until it forms one or more small plantlets. This usually happens sooner or later if you have the moisture, humidity, temperature, and light just right. If the leaf you are starting with is the entire leaf, including the part that attached it earlier to the "Mother Plant" then it usually begins forming plantlets earlier, but even a severed, partial leaf can produce multiple plantlets, it just usually takes much longer to begin.