The difficulty Apple faces with this is that the longer the existing system is in place, the harder it gets to replace it.
When you get a Push Notification, you MUST respond to it in some way.
Other mobile OSes allow you to ignore a notification or to respond to them in any order that you wish.
Ensuring that existing and future Apps can work correctly with a new system would be important. As would the possible mix of newer devices that support the improved system and older devices that don't.