Hi RainyDay,
Bear in mind that the 100% package doesn't actually qualify anyone for a bigger mortgage. If anything, the bids on properties will need to be slightly lower because of the 100% mortgage. (If your income qualifies you for €250,000, you can bid €250,000 for a property on a 100% mortgage. But if you have managed to save an 8% deposit, the same €250,000 mortgage will see you buying a property for ~€272,000.)
I'd suspect that there will be a temporary surge in First Time Buyer property-buying which will drive up prices temporarily. But the surge will only last while all those potential FTBs currently saving for a deposit forget about the saving and jump into the market now. That's a finite number of people. Once they've all bought their first homes, the market should level back to a point where all potential FTBs can get on the market as soon as their income is sufficient to qualify them for the right size of mortgage. That's a steady stream of people, comparable to the steady stream of people that were buying their first homes prior to the introduction of 100% loans.
Cheers, Liam