The whole GTF test campaign plus the press releases (which are quite frequent, you read something related in every other Flight International issue) surely have the purpose to generate publicity.

The business case for an A320NG with large winglets, GTF-engines and some other mods is often discounted but still kept alive (and the business case is not that terribly shiny). I am not sure about the strategy Airbus is following. It would be a reasonable move in order to pull Boeing in a position to launch a B737 replacement, which has two advantages:
– Boeing would not simultaneously launch a B777 replacement, which helps Airbus’ A350-900 and -1000
– being second on the market will be of advantage in case of the single aisle

Boeing could do the same with the B737NG (B737(NG^2)), but it already exploited the wing tip to full extend and also would have serious troubles putting the GTF under the wing. Additionally, the B737 trails the A320 in applied technologies and a third renovation of a 1960ies aircraft on such a high profile market doesn’t satisfy the customers (see B747-8).