They will often hold planes where a number of connecting passengers are delayed - depends what proportion of passengers and how long the delay is.

I've misconnected once with a 24 hour wait until the next flight (50 minute scheduled transit at old DOH airport with heavy traffic as leaving LHR)... I was looked after really well though with visa, hotel, meals, international phone calls and airport transfers all provided by QR. Ended up having a really lovely (if unexpected!) stopover in Doha!!

My baggage has made numerous tight connections - it was delayed once but delivered direct to hotel the next day.

1hr 15 transit should be fine. It's 30 mins longer than the minimum connecting time so you should make it even with a slight delay. Enjoy your flights - the A380 is amazing