Also worth considering: There is no one on earth you can pay to stop the worry you will have about your children, or from having the sheer mental load of sick children/stressed out teens/school issues/health issues/education demands and all the rest coming down the track.
The time your children actually need to spend with you as a their parent is considerable if you want well rounded, confident and happy kids. You can pay your way out of most problems to some degree, but as parents we need to be present, available and ready to help our children through some times some very serious problems. There needs to be someone there for your child that is not the nanny or the local maths tutor, someone to listen, to care and to hug them. Someone that truly loves them, and is not being paid to listen and care about them. Children need anchors. They need someone to steady the ship, this becomes more apparent the older they get. Plan in advance and have some real clarity about the potential hazards.
Children are easy when they are babies and tots, the real challenges often come later when they are teenagers.
Your dh may well have stopped working in the city by that point, and be able to offer emotional and practical support to older dc, but do look beyond the simple logistics of raising children, because much more is needed than paid help in my experience.
Teen girls need A LOT of support, of course teen boys do as well - you can't pay someone to do it. It is our job as parents to be invested in their well being. The more children you have, the greater demand on your reserves. It is a whole new ballgame, worth thinking through well in advance.
Who is going to be there for our children? Which one of us will be working, which one will be available? How can we do this so they don't suffer, and we are offering them the kind of life that is full of love, empathy and kindness and not just opportunity.
Never ever be tempted to live like multi millionaires either, even if you are on paper, you can get sucked into a lifestyle and the job can end in a heartbeat, and often whole careers before the age of 40. Live well within your means, and save. Be prepared for the day it all ends. As it will, perhaps sooner than you planned. Be prepared also, for it not to end quickly and you are older and the work is still just as ballbreaking.