Yes, the runway extension has worked out well thus far. I can't think of a single service that has been attracted specifically because there has been slightly more tarmac laid. Did Lufthansa come because of it? I don't it was uppermost in their thinking, although the aircraft does sound a wee bit higher as it roars over my housing estate on the first outbound at ~0530hrs...
If I recall, the outgoing owners didn't even construct the initial length to the north they stated they would, notwithstanding the hill to the north that is said to create a significant obstacle to any future lengthening in that direction.
I have often wondered if the owners - especially now the new owners - could extend both ends of the main to the peri roads (with attendant blast protection of course) & operate with displaced thresholds so that departures have the extra length, whilst arrivals touch down where they normally would as now, but then have the longer run off.
Just a thought and of course it all comes down to cost in the end, and exactly what investment Ferrovial & Co are prepared to commit to.