While I could retire at a SWR of about 3.5% of my current expenses, I am young, have not put the child through college, and expect to have significantly larger expenses in retirement than while working. I currently do not spend much money b/c I spend most of my time working, traveling for work or commuting to work, and my wife works also which means she has no time to spend money either.
I do plan to start a consulting business in the future at some point to transition into full ER, the plan being that I can limit working to 30-40/hours a week (currently 60/week including commute) by working out of the house and eliminating administrative overhead. The wife would also quit and would do the administrative stuff (billing, accounting, scheduling, travel arrangements, etc). I believe I can bring in 50-70% of our current combined income this way. While this would not allow me to continue to save (much), it would cover all our current expenses, allow me more free time, and give the nest-egg time to grow on its own.
The idea is that we would then fully retire when our child starts college.