St. Louis Cardinals fan here...
If I was presented with the world was such that keeping Pujols for the remainder of his career must be done at the cost of not winning another World Championship in that timeframe... I'd do it.
Seriously, one championship within a decade is pretty fleeting. Does anybody get worked up over St. Louis steamrolling the Tigers a few years back (except maybe a Tigers fan)? Meh... it's cooler to have Albert Pujols to root for everyday then to look at a World Series pennant. Unless you're a Red Sox fan (or maybe a Cubs fan... someday) you win the Series, you have about a week of fun with it, and then you're back to worrying about the NFL like the rest of the country.
Maybe I'd think about this differently if St. Louis didn't already have a bunch of championships already, but when I think of my team's history I think about the Musials, Gibsons, Ozzies, and Alberts more than which Championships we won.