On a off-topic side note, that’s completely wrong (at least in my country, no idea about yours).
The answer to your question is NO (as said, at least in my country). There is certain parts of constitution, and the “principle of democracy” and “principle of rule of law” are two of them, that can’t be changed by a vote; they are written down in the constitution as “unchangeable” (and that is “unchenageable” too) by any means.
The only way to change them would be by undemocratic means, eg military force.

I don’t even need to argue that a Law can be contested at the constitutional court, because it doesn’t matter. No matter if 2/3, 4/5 or all of the parliament would vote for such a thing: It is NOT possible (as said, at least in my country) to declare yourself as absolute ruler for life through a vote in parliament.
The guys who wrote the constitution of my country were smart enough declare certain principles as unchangeable even by vote. You’re free to think that’s good or bad, but your statement above is wrong in my country.

Completely off-topic and not important for your point, I know, but still…

The answer is YES. They can do that by 2/3 (or whatever it is prescribed) majority of votes. However there will probably be uprising of the people and they will depose them soon. By force.

It’s the same concearning FIDE and Ilyumzhinov. They CAN do that. But it probably wouldn’t end well for them.

And to answer Guillaume: Yes, they can do that. Ilyumzhinov would be World Champion then. However I would most likely stop following professional chess in that case.

But you confused me with something else: “changes during the cycles are unheard of”. ????? Did you miss lots of discussions here and elsewhere? Changes DID occur during the ongoing cycle – well, maybe all changes announced during the Dresden Olympiad will be nullified again. “Ongoing cycle” here refers to the one that will determine the challenger of Anand or Topalov (whoever wins their upcoming match – whenever/wherever that one happens, time, location and sponsors are not yet known ….).

Only for a brief period (between 1993 and 1996) there were two governing bodies. Only in that period there have been two World Champions for me. At all other time there was only one governing body – FIDE. Valid rules are the rules that are curently in effect. Frequent changes of rules are bad, changes during the cycles are unheard of. Still it doesn’t change anything. The one who wins the match/tournament/game/coin flip/whatever called “World Championships” is the world champion. It’s like that in any sport. Whoever wins the World championships is the world champion, irrespective of what he does at all other competitions.

Concerning your shorter follow-up post, I have my own “buts and ifs”: First, who is the “governing organisation”? During a certain period there were two, FIDE and PCA. Second, what (exactly) are the “valid rules”? – if they keep changing, not only between cycles but even during an ongoing cycle. Third, for me it is (and will always remain) legitimate to distinguish between tournament or match and KO lottery champions.

It is an addendum to the long post which is currently pending approval by the moderator. So you will have to wait a little to see it.