He could have retired at the end of the 2002 season and he'd have been a lock.
Problem that Lidstrom's going to run into is the lack of competition he had for the Norris Trophy. The runner-up for the Norris in each of his three seasons were guys who were 40-ish. (Bouque [and Stevens] in 2001, Chelios in 2002 and MacInnis in 2003). While guys like Niedermayer, Pronger and Blake have gone on to have fine careers, the quantity and quality of elite defencemen isn't what we saw 10 years ago, and especially 20 years ago.
I'd say Lidstrom ranks somewhere around top 15 or 20 of all-time. Orr, Shore, Bourque and Harvey comprise the top 4 on most lists. I'd say 5-10 are Potvin, Robinson, Kelly, Fetisov, Chelios and Coffey. Park would be ahead of Lidstrom, too, and I don't see Lidstrom surpassing Park. Lidstrom would be in a class with guys like Clapper, Horton and Pilote, and that's pretty darn good. Best defenceman drafted since Leetch was picked in 1986.