Let us instead pretend that we can see the future and humanity has survived so they must have found a way.
EDIT: The only way to stop the ignorant from messing with a system that is fair is to make the system so good to everyone that the ignorant do not bother to try. This is the long term goal of any civilised society, sadly no society currently rates as civilised.
In the future I see the following features in place to prevent the most egregious abuses of modern politics. In no particular order because all will need to be in place before humanity will survive and they accommodate and in fact rely on the strengths and weaknesses of human nature.
Open Source politics, there is total openness in all matters political, as in no secret slush funds and daily whistle blowing for those who care to read. (look into the roots of the GNU/linux movement and what powers the internet)
Global consensus on governance because we have reached a point where the pretence that resources and environmental harms can be ring fenced is over, all laws and policy must have "globally sustainable" as the first test and then other tests to follow.
All voting is personal, physica and secret, this prevents vote fraud, rigging, buying, coercion, hacking, supports apathy. A must at all levels of government. Secret voting eliminates the lobbying curse. (check out the Cardboard box reform for sound reasons)
Multi tiered governance as not everyone wants to have dogs barking and firework bans and people must be able to find communities of like minded people to enjoy life. Needing to DNA type all dogs so their poop can be attributed to their owners is taking it too far and that law should stay in some paranoid corner of the world where the people all want it.
Personal rights are supreme as long as you respect them (you must offer the same rights to all others). Presumed innocent, no slavery, right to replace your DNA (one clone or two sexually reproduced kids) but no right to breed others out of their share of the Earth, total freedom of movement. (look up Robert Green Ingersoll)
Citizens initiatives at any time are enough to raise a vote of NO CONFIDENCE in ANY elected official if they raise as many supporters as the elected official received votes to gain office. This will keep the elected officials honest to their election promises. (see writings on Demogarchy by Dennis Beckett)
Any tier can pass a law restricting only those they supervise as long as a higher tier has not passed a law preventing such a restriction of such rights. (There must be buy in to any restrictive law, this means the laws are just, necessary and valuable or they would not have been asked for, an easy way to get this started is that all law proposals must have come from a citizen driven initiative, lobbyists and politicians must educate the citizens)
and the last one that lets humanity survive:
Anyone can form a region of governance of any size they can unanimously motivate under or encompassing any others that have voluntarily accepted to this. The precondition for a region of governance is that they have a SUSTAINABLE (ie. 1000 year plan) budget to pay an agreed number of citizen dividends at the poverty line to every citizen they plan to govern. This is the only way that humanity can put a cap on population. If it is locally managed based on the available resource. Those who opt-in are the ones who have to see to it that their leaders have enough to sustain their poorest. (see Guy Standing and Rutger Bergman for reasons and ideas on Universal Basic Income)
(a few later additions)
There can never be a single leader at any tier for any purpose as this eliminated the voting, so 3 or more odd number of leaders. "Sadly the easiest way to subvert any important system, with leaders, is through the leaders." Kalle Pihlajasaari, 2015
All elected posts are volunteer posts. You get paid the citizen dividend like everyone else if you want to be a boss of others. If you have the skill to increase the GDP enough to increase the citizen divided then everyone gains and not just you.
Voting is totally optional and many people are expected to only vote when things are not working. The goal of the system is to be sufficiently OPTIMAL as in reaching a adequate working solution (like TeX that has a version number that asymptotically approaches perfection but never reaches it because the extra effort no longer brings detectable gains). Such a enduring system no longer needs the constituents to vote unless there has been a slow change in demographics of an area and the local majority want to ban dogs barking after 8pm.
(end off additions)
The last one makes politics into a mutually agreed on win-win situation instead of the serfdom that it is today where some incumbent says you have to pay taxes and maybe your vote counts for something.
(I may have forgotten some things but the idea is that it must be simple and survive for thousands of years otherwise the cost of continuously maintaining the type of system gets too high for no true value. We should have reached peak politics by now and be moving rather towards the plateau phase where things are predictable and beneficial to everyone.)
I suppose I should explain why the sustainable manifesto answers the OPs question. The basic premise is that eventually human nature will prevail as has been shown to work in all spheres of life. People will work to feed their families and gather to protect their communities (bucket brigades, barn raising, militia, hay days). What present day politics has done is take the will and common knowledge of the people out of the loop and replace it with propaganda manipulated bullying.
Human nature is such that people will do the right thing if they know what is the right thing is and it does not conflict with immediate survival. People just need a way to let those who want to rule that they get to rule if they get the job done and can keep ruling for as long as they get the job done but are out on their ear as soon as they no longer get the job done.
The thought that meritocracy will be a good system is flawed as it makes the primary presumption that someone else knows what is the best for someone else. Certainly a high standard should be expected in leaders but leaders should lead because they are capable and not because they are charismatic. The way to get rid of the junk and draw in the capable ones is if the junk gets voted out promptly and charismatic ones see the value in their effort.