From what I've observed the starting initial yield has two components:
1. Pure mispricing, misunderstanding of risk, etc.. where value investors make a living.
2. The real or perceived quality, safety, and long-term stability of the earning stream. Basically the higher the quality of the business, the lower the starting yield. Think maybe Coca Cola vs Dow Chemicals. Perhaps both make the exact same amount of free cash flow at some point in time but one may be cyclical, another less so. One might have less conviction that the earnings will be stable, not change, or materialize in 50 years, the other might not.
Seritage it's hard to say the quality of the earnings but if the value of the real estate is there and the land and development is good I can't see why it can't last a long time.