Ryanair is apparently serious about serving major airports. It was only in December that there was a large discussion about Ryanair wanting to serve to MUC but negotiations weren’t as fruitful. There was ofcourse the point of how much airport taxes it was willing to pay to serve MUC.
I think it’s very possible they could serve AMS. Those short turn-around times will hardly be possible on big airports. Then comes the question of how ‘high’ it’ll raise prices to cover the extra costs incurred. Though i think it’ll still be cheaper than most.