In a completely pointless exercise I have a spreadsheet that calculates Championship points based on the different scoring systems used over the years.
From 1950 to 1959 the Points were as follows:
1st - 8pts, 2nd - 6pts, 3rd - 4pts, 4th - 3pts, 5th - 2 pts. Plus 1 pt for fastest lap. Total 24pts per race
From 1960 the Points were as follows:
1st - 8pts, 2nd - 6pts, 3rd - 4pts, 4th - 3pts, 5th - 2 pts, 6th - 1pt. Total 24pts per race
From 1961 - 1990 the Points were as follows:
1st - 9pts, 2nd - 6pts, 3rd - 4pts, 4th - 3pts, 5th - 2 pts, 6th - 1pt. Total 25pts per race
there were also periods in here where although the points were the same, different #'s of races counted allowing drivers to drop their worst score. This did affect the championship outcome on some occasions
From 1991 - 2002 the Points were as follows:
1st - 10pts, 2nd - 6pts, 3rd - 4pts, 4th - 3pts, 5th - 2 pts, 6th - 1pt. Total 26pts per race
From 2003 - 2009 the Points were as follows:
1st - 10pts, 2nd - 8pts, 3rd - 6pts, 4th - 5pts, 5th - 4 pts, 6th - 3pt, 7th - 2pts, 8th - 1pt. Total 39 pts per race
For 20 10 the FIA decided to copy the SCCA autocross philosophy that every one has to go home with a trophy so started giving points to half the field. The points are as follows:
1st - 25 pts, 2nd - 18 pts, 3rd - 15 pts, 4th - 12 pts, 5th - 10 pts, 6th - 8 pt, 7th - 6 pts, 8th - 4 pts, 9th - 2pts, 10th - 1pt Total 101 pts per race
The good news is that in all cases Vettel would still be Champ with Alonstool 2nd. The first potential change comes with 3rd and 4th. The Convict would be demoted to 4th with all systems except the 91 to 02 system where he and Hammy would be tired for 3rd on points. With the convict having 1 more win I guess that would still give him 3rd over Hammy. You don't get any other changes until way down the grid where under most points systems Petrov would have finished 12th and Kobayashi 13th rather than the other way around as it is now.
Overall that's good news as the Champ is still the champ no matter how you cut it. I do recall people doing the same exercise many years ago and proving that Mansell would have one 1 or 2 more championships based on the change in the rules. One of those was changing the number of dropped races in the 80's. Even I'm not geeky enough to go back and check that out yet.