People who do commercial surveying have been discussing this a lot. While the RTK system does provide CM level positioning accuracy - it does not eliminate the need for ground control points for mapping and survey work. As a real quick primer for anyone who reads this and is not familiar with the RTK system, it improves accuracy by using a fixed GPS antenna on the ground in addition to 2 large GPS pucks on the copter to triangulate its position in 3D space. Instead of using position information from multiple satellites in space, the stationary ground antenna gets its position from all the satellites in space and then uses its fixed location to measure its distance to the copter and calculates its GPS position that way. The local and close range calculations allow a more accurate position fix. The reason you still need ground control points is because the copter can be moving at reasonably fast speeds and the ground station and onboard antennas can not stream the positioning data between them fast enough to maintain a CM accurate location at the time each photo is taken by a mapping or surveying program (and then write the data to the EXIF info). Until this is possible (at least with DJI) we will continue to have to have some ground control points for mapping and surveying to insure a high level of accuracy. As it relates to cinema work, the RTK system does help perform high precision moves and also helps with hovering position and altitude position. The other benefit for commercial (and cinema) users of an RTK system is that it eliminates the reliance on a magnetic compass - allowing for normal flying around areas of high magnetic interference (strong power lines, lots of steel structures, etc). The heading information is calculated by the RTK system instead of a compass - thus making it much more suitable for environments that give the magnetic compass problems.
If the M210 RTK uses the same RTK technology currently available to add to the M600, the above would apply to the 210 RTK. I have not heard if the RTK will be the same or if it will be different technology than DJI currently uses in their other RTK system.
Hope that helps a little - let us know if we can be of any further assistance with anything at all.
Michael
www.FloridaDroneSupply.com