I think this is a breakout from the 4 percent rule for real estate discussion.
Back in the late 1980's and early 1990's, when Really Big and Complicated Discounted Cash Flow spreadsheets became popular, appraisers and real estate analysts used programs such as Pro-ject and Office to model cash flows from large shopping centers, Manhattan office buildings, 500 unit apartment complexes, and the like. Discounted cash flow was touted as a more "accurate" way to estimate value than direct capitalization, because of the explicitly projected cash flows.
The models were very precise, but users noticed immediately that small changes in the growth rates of income and expenses produces very different values. Lots of banks and syndication investors lost a lot of money when the models were tweaked to benefit the borrowers and the syndicators. Watching that blow up substantially lessened my reliance on explicit net real estate income projections over long periods of time.
The 4 percent rule for paper assets is derived from various combinations of what actually happened in the paper asset markets over their histories, or at least their more recent histories with organized markets and exchanges. There is no corresponding data set for real estate income. There is is some fairly generic (and often inaccurate) rent information out there. Cap rates, gross rent multipliers, and discount rates vary over time, depending on the strength of the real estate market and competing investments. Expenses ebb and flow to some extent as well. Since market value is a snapshot on a particular date, you can use market conditions as of that date with some confidence to estimate value, if you do your homework. However, good luck modeling future cash flows accurately with the available information.
Yet, with all that uncertainty, investors are out buying real estate. Are we all stupid, taking on unmeasurable risks? My theory is that most successful small investors are practical, rule of thumb people that rely on relatively recent (i.e. the last 5, 10 or 15 years) trends to make decisions. The rental market in 1950 is not particularly relevant to them today. They are more business people than they are passive investors. They project out maybe 5 or 10 years, but don't bother beyond that. Projecting cash flow out 20 years is not possible, except maybe to guess current trends continue, more or less.
So, how does one "model" real estate income for a 40 year plus retirement? I don't have a good answer for that. Investment real estate is a business, not a collection of passively owned assets, and business conditions change dramatically over time, often over very short periods. I don't think any of the retirement income calculators model business income, at least not the ones I looked at. If someone has a good answer, I'm all ears.