Agree with most of what you've said but rents are set by the market, not by what landlords costs are. Landlords will always charge the maximum they can get, thats the business they are in.
It is utter bollocks. If you read the article, they have just taken the rise from the last few months and interpolated forward 10 years. It takes no economic factors into consideration at all.
We had similar forecasts in 2007 after similar steep rises just before the credit crunch.