Though it is questionable how much a theory of quantum gravity would affect every-day life. Physics hasn't made much progress on that front precisely because it's far removed from the human scale.
I think we still have some tricks up our sleeve for "conventional" technology:
- Space Elevators might never be built
- a warp drive will almost certainly never be built
- Fusion reactors are likely within reach, could potentially even have been achieved already but for ecomomic reasons and policy decisions, though I'm not sure how much of a game changer they would actually be
- AI Humanoid Servants (and related breakthroughs, eg brain simulation: forget warp drives, think about the ability to 'fork' a person, and have that version of yourself embark on a centuries-long journey across the stars aboard conventional space ships), I'm with you