Net worth discussions like this are very interesting–especially when the stats reveal that about 95% of US households are relatively clueless concerning the realities of how much they will need to comfortably retire.
As UCGal mentioned, and as the OP noted, I agree that having around $2M saved, or a comparable pension, etc., from around age 60 on should work out for most people. $2M for someone who wants to retire at 40 would most likely fall short, but, we’re hoping maintaining $2M (not inherited, and not including real estate) till we’re 60 (we’re now 54) will do it for us. After that, the only concern for all of us will be having the health and longevity to continue to enjoy our lives!