You have to weigh the options and cost on a modernization or maintenance.
Sure ,you could let it go to Otis to maintain it as long as you are willing to pay the price of maintaining it,which will never happen because of all the labor cut backs and lack of experienced people to work on it.
The parts are available,the knowledge is sometimes not.
It would be a good idea to go non-propitiatory so anyone could work on it and there are some good products out there.
