Yeah, my emergency plan was just what daverobev said- go back to work. Kinda depressing thought, but it's better than being there everyday. Vacancies are another issue. I would have a $5k or so buffer between my annual spending (which I could easily trim if need be) and what my rentals are bringing in, and I would have 4 or 5 of them- the odds of multiple vacancies is something I'm hoping doesn't happen often. It might be worthwhile to just push the retirement back a year or so, but there's a lot of sacrifices I'm going to be making to reach my goal in 4 years, so I guess we'll see.
I have several military readers who have retired on their military pensions with very little savings-- one has saved less than $50K.
The key is having a source of income that you can depend on despite catastrophes. For some that might be a govt pension, for others an annuity, for still others it would be rental properties that still throw off cash even if you have a 25% vacancy rate.
"Multiple vacancies" may seem unthinkable now, but what happens if your properties are within 20 miles of each other and something happens like a military base closure or a poisoned water table... or even "Detroit"?
The trap is that you might be able to live on $10K/year (or insert number here) but during the good years you'd adapt to the hedonic thrill of a $25K/year budget. Going back to $10K/year might be absolutely unthinkable. If it happens when you're 72 years old then you're not going to be very happy about getting a job, either.
In some cases, the "retire with zero savings" plan is a proxy for "I need to change my career, or at least my employer". If you have enough to retire with zero savings now (yet some risk of implosion) then why not change your career/employer now? You have a great safety net in place and the financial freedom to discover something that you really enjoy doing.
If you feel it's a case of Your Money or Your Life, though, then start living on your retirement budget now and see how you feel about the situation in 2015.