I think they'll offload Mahrez in the summer.... or maybe in January if Messi comes. I'm not sure if they'll get him in January or not, but they could easily afford him and it won't affect them in regards to the FFP all that much, especially if they offload Mahrez.
It doesn't matter in any case..... Messi could easily sign a pre-contract in January and sign for City for free in the summer. Font cannot do anything about that, so I have no clue why he's going on about Messi winning the Champions League in the future with Barcelona. He knows damn well that we're miles away from the Champions League, and he can't expect a 34-year-old Messi to carry us like he used to.