It seems that in this example you are pegging the price of flowers to the price of electricity in cross reference to the mining difficulty. This seems extremely roundabout.
If miners continue to do what makes sense, the difficulty will grow alongside the price of Bitcoin. Which will lead to a commensurate increase in the cost of generating one Bitcoin. Essentially the price of flowers will now follow the difficulty curve, which follows the price on a delay.
Thus it takes minute-to-minute volatility out of the equation, but incentivizes just watching the price all the same so that you know what will happen.
Your reasoning sounds about right. However, I would also include miner's equipment depreciation and other operating costs. At the end, miners would pretty much make a stable return on the general ledger rows that they make available for public use, whereas the public (merchants, consumers, etc.) would increase the applicability of those rows to real world trade by increasing their use throughout the daily exchange of goods and services between themselves. Eventually, miners will eat away (via transaction fees) all of the existing rows to make them available for public use once again at some future date (but perhaps at a higher cost, provided that bitcoin economy grew)... And a circular dependency continues, so to speak.