don't forget the 1.5 engine is being used in the VW, Audi, Skoda and SEAT models, so if an increase in orders for this engine in another VAG group i.e. VW T-ROC, then they will supply to the them and supply will be reduced to the other makes. VW(VAG) controls this and they are going to want there models out of the door before its sibling makes.
The 1.0TSI is less likely to be effected so much as this is mostly going to be spec'd in these smaller models, Arona, POLO, Ibiza, Leon, UP! GTI, etc..
it all depends on supply and demand, But VAG not going to say this directly.