It's hard to say at age 33 and being quite far from financial independence or retirement, what retirement number I will need.
I think if I could manage to get 10 houses under my belt that rent for an average of 5-600/month real cash flow per month in todays dollars (some may be paid off, some not) and 20 years more 401K from both me and the wife and all personal debt paid off, we would be pretty good.
I suppose that would be about 5500/month from rental income plus around 1.5-2MM in real estate assets plus around 0.75 to 1MM in 401K monies.
I think the 401K monies, however we decide to invest them post 401K will provide a nice and truly passive component in with the rental money that should still increase with time as remaining mortgages get paid off. I would manage the rentals and that would be my work in retirement. I may do some other type of work if I find I spend too much money in my free time and get bored otherwise.
I think being a Walmart greeter would be a nice and stressless retirement job to pay for my coffees and sandwiches. Maybe a plant waterer at a botanical garden...