As a side note, I don't know if this is always true, but in my case, I would keep my health/dental/vision protection during a sabbatical (pre-paying corresponding fees, my part, not the employer's part). So it wouldn't hurt to take a sabbatical for 3 or 6 months, come back for a couple of weeks, resign and early retire... With the backup option of actually resuming work if a) turns out you have a change of mind b) circumstances change (personal stuff, stock market crash, whatever).
And yes, I am planning to do something like that...
And yes, I am planning to do something like that...