Yes it would be okay to let your child or children wear diapers forever.
You should not ever potty train your kids or child and let them stay in and wear and use diapers forever or at least as long as they live with you.
Diapers are much better than using the potty and it's healthier as well.
When wearing diapers you don't need a potty break or have to hold it to use the toilet as the diaper is your toilet and you can simply pee and poop in the diaper later and change it or get it changed when it's needed.
Diapers are also more comfortable than plain underwear or boxers and they feel even better when wet and squishy.
To convince your kids to go back to wearing diapers get rid of all of the kids underwear.
Then put the kid in diapers yourself.
Discuss with the kids how much more comfortable diapers are and discuss the convenience of the diapers.
Keep telling the kids how easier it is to use diapers for pee and poop instead of wasting time going to the toilet.
With a diaper they can go potty anytime they want too and need too without having to hold it.
If your kid does not voluntarily wear the diaper you should make them wear it yourself.
After awhile they should get used to wearing diapers and decide they would rather wear them.
It takes time for the kid to get used to wearing diapers if they are not already a diaper lover.
Eventually your kid will most likely grow to love diapers.
Personally I would never potty train the kids to begin with and keep them in diapers.
If your kids are kept in diapers all the time and never potty trained then they will not need to be convinced to wear diapers again.