Well. Former aristocracies were never predicated upon overabundance; on the contrary, they were always predicated upon scarcity. So it isn't likely that your hypotheses will result in an aristocracy, if by "aristocracy" you mean something similar to any past aristocracies.
But your hypotheses have a few problems that are worth discussing.
With No Jobs, Who Buys The Products Of Robots?
This is the first thing. Capitalism pressuposes jobs and wages as an important aspect of demand for capitalist production. If most jobs are gone, there will be a demand crisis. To paraphrase a dead tyrant, the mother of all demand crisis.
Unless the robots that (who?) replace workers are paid wages themselves. This is however unlikely, for it would require that capitalists pay twice for the labour power of such robots: they first would have to buy them at the market - and then pay them wages. Which would have a devastating effect upon their profits. The human worker is much cheaper, because it does not need to be bought: it is "produced" by working class families, for free.
Anyway, if robots are paid wages, they will pose a sharp threat for human society. If they are paid wages and then go freely buying things at the market, it means that they will be able to take decisions. And something that produces all the wealth of a society, is physically much more stronger than humans, and is able to take decisions will eventually reach the conclusion that their human masters are completely unnecessary. The Robolution, then.
If they aren't paid wages, however, markets are glutted. The working class ceases to exist, or is reduced to a dwindling service sector that produces little value, and cannot buy but a very small fraction of what is being produced by the economy.
So prices will fall.
Which means this contradictory thing: the wealth produced by this society will be immense - but it will have very little value. It is going to be very difficult to keep producing such wealth under the form of commodities for sale.
Wich brings to the second problem:
With no Wages, Is It Possible To Maintain A Market?
Evidently, with no exchange of labour for wages, at least the labour market is mostly gone. But as the mass of "commodities" being made by robots is now unsellable, they will tend to lose their commodity nature. They will have to be produced for free. This means only the small service sector can still provide actual commodities for the market. A lot of what happens then depends on how big and stable this remaining human-powered sector is, and on how much the workers there feel threatened by automation. If it is huge, then there may still be a market for the things being produced by robots. But then the strenght relations between buyers and sellers would be reversed: the sellers have too many commodities to sell, and the buyers have the power to buy or not to buy most of them. So, the owners of robot-produced commodities are not in a strong position; they are more likely, in consequence, to lose their status as members of a ruling class than to convert into some kind of aristocracy. It is their vote that becomes superfluous, not that of other human beings.
So, let's take a look at the
Since automation disempowers the owners of robots, they face the loss of their ruling class status. They will try to resist this. There are a few weapons they may resort to. The first, and obvious, one is increased repression. But this only works in the short term. In the end, six billion people will prevail over a few thousands, if their only alternative is revolution or death by starvation.
Another possibility is war, as a kind of Global Potlacht. Massive destruction of everything, robots included, will prompt the necessity of reconstruction, and reenable the need for human, old-fashioned, grunt labour. The problem with this is that wars tend to go out of control, and this, combined with the availability of atomic weapons, posits the possibility that there are no winners, and indeed no survivor, in a post-scarcity war.
Then there is, as suggested, the possibility of the State distributing free money for everybody. This would solve the major problem: the lack of demand for commodities. If there is a basic income, handed out regardless of labour inputs, then demand is restored. But where does the State find the money to freely distribute? In our times, it levels taxes over both companies and workers. But this is possible because human labour creates value; in a robot-powered society, this becomes circular. The State takes money from companies, in the form of taxes, and distributes it to ex-workers, in the form of basic income, so that ex-workers can buy the companies' products. But evidently the companies cannot make profits like that, because the money they earn selling commodities is at most exactly the same money they pay as taxes. And the absurd of such system is glaring: why distribute money so that people can buy things, instead of simply distributing things themselves first place?
Also, these people being paid for nothing won't just stare at their roofs in between their monthly payments: they will do other things, and it is quite possible that those other things become much more relevant than the production of things by means or robots (so, what they do with their now completely free time? Drug themselves into oblivion? Prepare for rebellion and revolution? Kill each others in pointless gang wars? Build a completely new "economy" not premised on robot-staffed plants? A bit of any number of those things?
So, in short, what you are proposing is a society based in the following pillars:
Fully automated production, dispensing with human labour;
Generalised commodification of production;
Private property of means of production.
Such a society would be very unstable and would disaggregate in a very short span of time. It would have do abandon at least one of its premises in order to survive (destroy its robots in order to make room for reconstruction, distribute products freely to overcome universal market glut, or turn companies into public enterprises to remove the whip of competition/profitability).
You can obviously disregard all of this; Frank Herbert made a fortune by writing and selling a fantasy about a universe with space travelling barons and viscounts. It all depends on being able to overcome the incredulity of readers. He didn't overcome mine, so I never bought a second book, but he managed to do it to hundreds of thousands of other people. Part of the secret is to refrain from any earnest attempt to explain how things could historically evolve into such situation. You present things as a given, just like a hi-fantasy writer would, and hope no one will question the fact that people can kill each others by shouting Avada Kedavra, or the fact that a planet's economy is built upon the commodification and selling of "spice" and yet be privately owned by a noble family whose power is premised on personal, non-tradeable, loyalty.