There are probably 4 likely outcomes from this ruling:
1 - Airlines will devote more resources to aircraft maintenance and flight reliability, both reactive and preventative
2 - Fares will go up
3 - Reliability of flights will increase, both in terms of %'age flights completed and %'age of flights with no more than a small degree
4 - Airlines will be less inclined to experiment with smaller airports where there are fewer engineering resources in case things go wrong
Aircraft reliability costs money. Nobody wants to pay for it, but when aircraft go tech, airlines just point to the contract saying "we will get you there at some time of our choosing or refund you your money" and passengers end up screwed. Happened to me earlier this month.
Ultimately, it's all a big policy decision. How much of a safety net does Europe want to ensure flights are reliable and on time ? How much do people value their time to avoid lengthy flight delays ? Are we as a society prepared to pay for the safety net of reliability and back-up, or do we prefer to have a wider variety of flights for lower fares but suffer lower reliability ?