I've been giving a little thought to the first decade of this millennium, and the changes to F! in those 10 years. Only 3 teams are still around, in the same form, that they were at the start of 2000:
Ferrari, McLaren & Williams.
Teams that have entered F1 since 1 Jan 2000:
BMW Sauber
Brawn
Force India
Honda
Jaguar
Midland
Red Bull Racing
Renault
Scuderia Toro Rosso
Spyker
Toyota
Teams that have left F1 in the same years:
Arrows
BAR
Benneton
Honda
Jaguar
Jordan
Midland
Minardi
Prost
Sauber
Spyker
Toyota
Tracks that have entered F1 since 1 Jan 2000:
Abu Dahbi
Bahrain
Fuji
Indianapolis
Istanbul
Shanghai
Singapore
Valencia
Track that have left:
A-1 Ring
Fuji
Imola
Indianapolis
Magny-Cours
Montreal
I compiled these lists rather quickly, so I'm sure I've missed a few. I've given tracks and teams that are still on the fence, like Silverstone, the two German tracks and Renault, the benefit of the doubt.
Just a starting point for discussion of the changes.