I believe they are working on it. Already certain software releases are not required to be pre-approved by the FDA. For example the recent Dexcom G5 Mobile v1.7.3 for the iOS 11 did not require an FDA pre-approval. It was simply being updated to be compatible with the new Apple iOS. Certainly it is possible some tweaks were required but that falls within what is allowed. Similarly, updates for security fixes are also not required to gain FDA pre-approval.
The FDA however is taking this much further:
FUD: New FDA program pre-approves tech to speed medical progress