I am almost 71, we have two rental units. There are pros and cons and lots to consider in all of this.
Will the kids always stay where they are now? Guarantees?
I am going to make some assumptions and probably ask some questions/give some opinions.
Hiring the management company is not a bad idea if you do not want to handle all of that. I assume they advertise, show, do move in inspections, gather fees, deposit money, do checks and move outs? I would ask who they have do work if you need it. Do they do regular checks on the home i..e smoke detectors, clean gutters, fallen limbs, etc. I assume you will pay for that stuff. It does add up.
As for income, it is considered passive income so you are somewhat limited as to what you can deduct. Certainly all fees and costs associated with the home. You cannot deduct any of your labor.
Also assume you will be working on a 1 year lease. What would happen should you need to move back in that time?
I know the odds of this happening are small but there is always the issue of what happens to things if something happens to both of you? If you have a will only, the rental is tied up in probate which means some things like repairs, kicking out tenants, etc can become tricky as no one actually manages the property besides the court. If you have a trust, that is different and the property goes to the trustees you name and they can take care of any including rent, repairs, even getting into your accounts.
Back to the income part, yes you will have income to pay taxes on but you will also have expenses to deduct. Any repairs you make that are major like a new HVAC system have a specified depreciation schedule so you will want to run this all by an accountant.
On our two units, we set financial goals of netting 13% on our units and have done that consistently. We also do all of our own work aside from roofs and HVAC and my wife does all of our books. By the time I am 75 I expect we will begin to consider selling them which triggers a capital gains. You may also want to check into that piece, going from a single family home to commercial property, not sure how the capital gains works.