First, definitely put the cash in the money market to better use. That's too much cash to have sitting around when you're trying to grow the nest egg.
Second, I wonder if its time for your wife to say goodbye to the cubicle life and pursue other more mustachian pursuits? You already have a decent $400k warchest built up, and if you stick to mustachian principles, I think the both of you could easily live off your salary and continue to save a good chunk. In addition, while enjoying the fact that she no longer has to work a 9 to 5, your wife can explore other ways to generate passive income.
My cousin's family unit went this route and it has worked out great. His wife quit her full time job two years ago to focus on buying and managing rental properties. She now manages a number of properties which are paying for themselves while at the same time generating a modest income stream. Once they reach a second "tipping point" he can quit his job and join the rental-property project, or perhaps pursue something completely different.
While you work a bit longer, she could make the leap and blaze the path...