Don't be too sure... a lot of things people thought would happen didn't... picture phones, colonies in space, synths replacing instruments, electric cars, laser guns, and personal hovercraft to name a few. Often, tech reaches a plateau. Cars aren't that much faster than they were in the '60's. Guns still use the century old 9mm and .45 ACP and the even older 12 gauge. And you still often see old style C-9 Christmas lights on houses.
That argument can be so easily reversed to say, "a lot of things people scoffed at are now reality."
Star Trek portable phones. The ether disproved in favor of a vacuum that constitutes outer space. A manned mission to the moon, hell rockets that work in space (scientists scoffed at the idea that a rocket could work with no surrounding medium). Even a lot of the things you mention are vastly superior to when they came out.
1. Picture phones? What do you mean? Phones take pictures, do more functions, and have the capability to video conference with people now. An ipod has more computational power than the entire Apollo 13 spacecraft.
2. Colonies in space - Astronauts live year round in the ISS and private space companies are now looking to develop the technologies to shuttle 80,000 people to Mars and back each year.
3. Synth instruments - computers can accurately mimick the sounds of any instrument now. Whether or not you want to consider that art is up to you. I personally prefer to hear a person play still, but how would I know the difference on the radio?
4. Electric cars are around, not sure what you mean. They are still expensive, which is why researchers are looking for ways to bring down the cost. In one of my sci-fi short stories, the US ditches conventional vehicles for an electrically powered "grid" that cars ride along like a train. Everything is automated and the chance of an auto accident is slim. That might not be feasible in terms of $$$ but it is most definitely possible within today's technology.
5. I'll have to hand the laser gun to you. We still don't have a phaser from Star Trek. We have lasers that are so powerful that they could literally eviscerate a person though, its just that their oh so big.
6. Hovercraft will be reality in 30-50 years. Will they be personal? Probably not. It would be hard to take a society prone to car accidents and then give them flying cars, but superconducting materials in EM fields make it possible.
7. Cars come with more features than ever now, and while still petrol-based are way more efficient than older cars. Google is pioneering driverless cars, and while the whole process is still prone to complete failure, its on the right path.
8. Guns use the same ammo but the efficiency of guns has improved a hundred fold since their invention. Certain sniper rifles can pick off a target from a mile away. There are now smart bullets that can track a laser to a target.
9. Christmas lights are probably more due to the culture. I wouldn't bother buying new Christmas lights if my old ones are still bright and they'd be the same colors anyways.
You are right that technology hits plateaus, but only for a certain technological era. The bronze age hit a technological plateau, then advanced into the iron age, etc. We are in the information age of computers and technology and are on the verge of passing into the quantum age once quantum computing becomes viable, which will in turn allow us to discover even deeper mysteries about our universe and derive technologies from them. Will we ever become masters of the universe with technology? Maybe, probably not, since my own personal belief is that the universe is probably an infinitely layered mystery that goes on forever (not infinite in size, but in complexity). Even if we could probe down far enough to examine a single string in string theory, we'd just discover more laws governing the string.