It should be possible using automation. I prefer Macrodroid, being easy to learn and free (upto 5 macros)
Note: Not tested on Nougat ( I don't have it)
The macro would look like this ( on the left is the macro) and on right is detailed configuration for second action Display Notification

Explanation:
Your messaging app (Textra in my case) generates a notification which has hidden in it - This is the trigger ( you can choose multiple apps as I see from your screenshot, you have two apps)
First action is to clear such notifications
Second action is to substitute that notification with your customised message - you have a message in the example
This is the bare bones macro , you can play around with it and confirm whether it suits your needs - you can customise a lot in the second action by choosing options from ...
Clicking this on lock screen will NOT launch your messaging app. If you want that to be done create another macro, where
Trigger: Empty Trigger
Action: Launch Application → select your messaging app
Constraints : None
Name this macro whatever you like (say, launch messaging app ) and on the second action of first macro tick Invoke macro when pressed and choose launch messaging app
For a rooted device ( and when Nougat gets xposed ) , SMS Xposed has hide sender , hide message options