Mea Culpa. I must apologise as I misunderstood what the weather template entity is doing. My above question was: will the templates for the forecasts generate data for the service calls. I asked that question before, only to be met an answer that I took to be that I should keep using attributes. From that I wrongly assumed the weather templates would still create deprecated attributes too - I misread the above answer and the documentation (which does not describe what the forecast should look like by the way).
I just tested it, and they don’t create attributes. So to answer my own question (in case any one else wonders the same): the forecast templates are used to implement the new forecast services. If you provide them, the template weather entity will work with the new services. I thought they didn’t. So I must agree that is is not half baked - I just misunderstood. Apologies.