Well I'm not sure why you expect some utopia. Even if we manage to get through the technical hurdles that remain and fusion power becomes commercial why do you imagine the price of electricity will drop to 0? The fusion reactor costs money, the operation of it costs money, etc. It is unlikely that a banana republic will be getting one soon so there will be no free power to everyone....just like now there is no push to give every village in africa its own wind turbine (personally I think that is a better use of wind turbines then what I see when I look out the train window) or water source.
The fact that in aurora you can move 10,000 tonne ships, jump to other stars and reprogram your genetic code doesn't mean that a communist (not a marxist-leninsit type) situation exists where everyones needs are looked after, any more than our progress since the 1800's has resulted in the betterment of more than small fraction of the populations lives. My feeling based on my military leadership training is that communism won't work since it seems to be based on the absrud assumption that leaders will not form.
I don't expect a disatopia but "Star Trek" I doubt ever will form...Gene Roddenberry had some rather odd ideas. Though I must admit I had a lot of fun with the Klingon suplement for Star Trek The Role Playing Game (by FASA)...the Klingon's view of the Federation was priceless. It was the "Earth Empire." What I saw on the second abomination was just too much to take. But then replicators in the orginal series were far from the things you saw there...and they apparently didn't realize they had the font of youth (save the transporter buffer). But my mind boggles on any economic system that could provide for the wants of everyone. The needs yes, the wants no. And largely it is the wants that drive our economy.
Auroras races eat themselves out of house and home, constantly searching for new minerals to feed their need for them. The NCC has 3 minearls on the watch list now: Venderite, Boronide, and Gallicite. All three are low though the Gallicite production is now so ramped up that the stock pile grows. Boronide being low has meant no new terraformers, or refiners in the last several years. Vernerite has been historically low but the demand is low so the production-use has been balanced. But it is a constant balancing act to keep minerals flowing in, not in Sol production is also ramping up (slowly admittely) yet the minerals flowing in from Alpha C are a good part of the total production now...Biforst sent in load of 5x1000 units of various minerals and the posibility of inter colony trade is there now between Arboria and Forge. Still the source of all of this is the CMC. Just like the growth of the colonies in Sol was due to the civillian freighters moving people and goods. When the NCC finds out jump gates are possible I forsee at least a few being built to open up Alpha C to the civillian trade...it has industries producing goods in high demand in Sol.
Ultimately taxes will remain taxes. Governments need money to work, that is something that has been true since governments were formed and I don't see how that can change. Even discussions about the new energy market, more or less can't avoid the fact that "someone" has to pay for the new power distribution system. And power companies barely want to invest in the current system (understandably so)...not to mention the other costs associated with renewable energies. Then there is the social net...the cost of that is a major part of government spending. I don't see that going away. And someone has to maintain all the infrastructure, plus regulate it (remember Adam Smith said more than "let the market alone" he also said "but watch the people who play in it"). All this costs money.
Inevitably I think in Aurora you will end up with the weathy wandering around in smart suits, eating off duranium plates, being chaufered around in grav cars while the masses live somewhat less splenditly. But probably much better off than we are now. The crimson world books may be of interest to people as they deal with the disporia situation...unfortunately with a Earth government that sets my teeth on edge. I am starting to despise the whole "government is evil" schlock. In the case of the crimson worlds I am finding it hard to believe the intellegence service can wield so much power--but that is a matter of taste.