I think that with modern snapshots, it would be interesting to create a 'cloud backup' service where you have a 'do not allow overwrite before date X' parameter

I think that with modern snapshots, it would be interesting to create a 'cloud backup' service where you have a 'do not allow overwrite before date X' parameter, and it wouldn't be that hard to implement, but I don't know of anyone that does it. Does Amazon Glacier offer this?