Luke 21:29-36 — 'this generation' in Luke: the generation that sees the signs, not the first century

The fig tree parable in Luke: when you see the trees bud you know summer is near — when you see these signs (cosmic signs, Jerusalem no longer trampled) you know the kingdom of God is near. 'This generation' = the generation alive when all these signs are taking place. The warning at the end (v.34-36) is against dissipation, drunkenness, and cares of this life, which are spiritual dangers during the long delay. The longer the delay, the greater the temptation to get comfortable in the world.