Well one thing she should do is save up/wait until the kids are significantly older before doing this sort of thing. My mom went back to school in her 50s to not only get her masters degree but also PHD. I can't imagine what it would have been like had she done that when we were very young. She didn't start work on her masters until nearly all of her kids were out of the house/able to take care of themselves entirely. Also our financial situation was very comfortable yet she still got grey hair on half of her head after the whole ordeal (she dyes her hair now). Working towards that PHD, she basically had to scrounge for all the time she could get, I can only imagine what med school would be like.
Just remember this, your wife likely won't be making significantly more money than she is now, will have to deal with insurance and all of that shit, not to mention the stress of the job and whatnot. I know people who work in medicine and Obamacare is going to make working in medicine extremely unappealing compared with what it is already.
Your wife being told that she is so smart and that she should work in medicine should be taken as a compliment and just that. Both my mom and I get that shit all the time but I understand that the effort to reward ratio in being a doctor is absolutely terrible and is about to get worse. I'm sure I'd be "great" at a lot of things but there are good reasons not to take those jobs.
Going through and finishing medical school is difficult enough, it will take years off of your life and once you're finished, you'll be doing a thankless job anyhow. Honestly, knowing your situation now, if she tries to dive in and go to medical school, it will likely be ruinous for your relationship, your family and her. She will probably get floaters if not a full blown detached retina in her eye(s) due to the excessive stress she'll be under, her hair will go grey, and she'll look ten years older... for what? To live up to OTHER PEOPLE'S EXPECTATIONS? It's not worth it at all and frankly it sounds like she's got a pretty good gig...
Also I think it's comical that she can be burnt out by being a pharmacist yet is considering a job path that is so much more strenuous and stressful. If she can't handle being a pharmacist, being a doctor will kill her unless she plans to go an easy route of being a GP in bumfuck middle of nowhere... (Good luck with that!!!)