$600 / month for health care for a family of four?
What will your adjusted income be? I guess for the first few years it would be whatever dividends you received in taxable accounts, so you would get a pretty good ACA subsidy because you could spend down your cash buffer and pull out the maximum from your portfolio that won't gum up the subsidy. That might add another year or so..
But once you have to start withdrawing each year to maintain your spend rate that's not going to work.
While you are doing the minimal withdrawals you could do them from the biggest capital gains stocks. If your income is low enough there's no tax, and it's fairly low otherwise. That will help long term. But long term capital gains rates are fairly low, so that's not a huge problem.
Your spend doesn't include taxes, so those need to be factored in. If you were stuck paying 15% on ALL your withdrawals (which is unrealistically conservative), your annual spend would be about $94,200, so let's round that down to $90,000.
That's $90,000 / 2,400,000 or a 3.75% withdrawal rate (WR). That's reasonably conservative and we all (should) know the 4% WR is pretty safe to begin with.
So, in principle, you're good to go if your spending estimates are correct.
These are the risks I see:
1) Do you know that your health care estimates for monthly insurance are correct? Are these high deductible plans where you might be out an additional $10,000 a year if you're unlucky?
2) Are you sure the rest of your expenses are close to correct?
3) You have a lot of your wealth in a fairly small number of stocks. One Enron or JC Penney bankruptcy would hurt a lot.
4) Do you have skills that would get you re-employed fairly easily? Or are you very specialized and would find it hard to find work again?
When I make important plans, I plan two different ways:
1) I plan for success. I come up with a plan that will reach my goals.
2) I plan for failure. I look at the ways my plan could fail catastrophically and leave me with an unacceptable result. Then I make a new success plan that mitigates all the known catastrophic failure reasons. An obvious test for a catastrophic failure possibility would be your single stock that holds 40% of your net worth becomes worthless before you can sell it off at a decent price. Your withdrawal rate would go from 3.75% WR to 5.9% (pretty darn high) but all those realized losses would help with the taxes a bit. A $20,000 job would add about $15,000 to your pocket, which would drop you to a 4.9% WR. A $40,000 job would drop you back to about 4%.
You would have a number of years to make adjustments and since you're willing to go back to work as needed, that's not a catastrophic failure.
But hey, this is MMM's website, so I have to ask, "Can't you lower those expenses a bit?"
But I think it looks good.