If airlines do move to a fixed cabin, I for one would welcome that.
Business class in Europe is lamentable on almost every possible level and you would need to be desperate to pay the sort of fares demanded for the service and product provided. This is particularly true if departing from t3 and the bus ride around the building site) No matter which carrier you choose if you are availing yourself of the £49 or £69 upgrade offers, then business may be attractive, but to pay in excess of £400 to fly to FRA is bonkers.
Compare the service in Europe with that delivered in Asia and offerings by MH CX SQ et al for flight up to 3 and 4 hours. These flights are packed and the yields on point to point excelent.