Frontier obviously created the new scan mechanic as a TIME SAVER.
How do we know this?
Think about it. The current time sinks for exploration are as follows:
1) travel to object
2) scan object
Under the proposed system we have:
1) scan object
2) lob probes at object
…
From what I've read and how I understand it the new system is:
drop into system
stay stationary to scan (with the discovery scanner) signal sources - that will include planets, asteroid belts, stations, USS.
If an object is scanned/identified with the discovery scanner all information that currently require the discovery scanner and detailed surface scanner is revealed for this object.
At this point the player can decide if an object is worth doing surface mapping using the new "shoot at it with ammo" detailed surface scanner.
1) scan object
2) fly to object
3) use probes to map object
The difference between new and old system is, that in the new system all the data we can currently get from an object is collected in one step.
Getting a basic system map isn't possible - in the new system it is all or nothing.
In the old system the player can decide if a detailed surface scan is worth it or if a basic overview of the system is enough.
This increases the time in the new system as a quick overlook of the system isn't possible anymore. The new system (probably) reduces the time needed to do a (current) full scan of a system as it removes the need to fly to the various objects.
The gameplay with probes is an addition to the current gameplay. It could be added to the current gameplay without any change to the new probe gameplay.
A compromise could use the old and new gameplay mechanics and combine them.
A honk shows the basic system map like it currently does.
The new signal source scanning function of the discovery scanner then collects the detailed surface data and reveals USSs and other signal sources.
The player than can decide if a surface mapping is worth doing.
Sidenote:
I think the new discovery scanner could be implemented as a HUD overlay - like the yellow and blue lines around objects. This would prevent the player to be "blind" in SC, allow the player to fly around and scanning object and maybe make scanning easier or faster if closer to the object (more involved gameplay).
I'm not sure how the new scanner interface will be implemented - maybe it is a HUD overlay and not like the current system map.