The product called Solidworks, as folks know it today, has already split into two development streams. Solidworks will stay as it is with the same modeling kernel until and beyond the time when development is halted in the future. For CAD, a modeling kernel is analogous to the engine, drive train, and chassis of a car. Solidworks V6 (now called Solidworks Mechanical/Conceptual and other solutions will be added) will be the new product that will take over Dassault's development efforts and it will be based on Catia's modeling kernel. If they wish to avoid any data disruption, Solidworks users of today will need to continue using today's Solidworks in the future even though there will come a time when there will be little to no further development effort put into the product.
Dassault will give incentives to entice existing Solidworks customers to move to Solidworks "V6" (Mechanical/Conceptual) even though there will not be true data compatibilities. Solidworks "V6" will likely have the ability to open a native Solidworks part, assy, or drawing with Solidworks V6, however, the data will surely be stripped of any intelligence that it once had. They will probably also say that drawings will come over fully associative but there will only be a small amount of truth to that statement (probably just model and drawing at the file level - views, notes, and annotations will need to be "cleaned up" afterwards with significant effort).
You will probably hear from your users something like: "they wouldn't do that to us loyal users." Another comment you might hear is: "they would never do that because they would be shooting themselves in the foot." Well, unfortunately, this kind of thing happens all the time. This is strictly a business decision for Dassault.
The reason why Dassault is doing this is Solidworks was written on the Parasolid modeling kernel. Parasolid is owned by Siemens. As a result, for every seat of software that Solidworks sells, Dassault must pay royalties to Siemens (one of their biggest competitors next to PTC). In addition, Dassault's flagship product is Catia and not Solidworks. They make significantly more revenue on Catia than on Solidworks. The sales of Solidworks will eventually hit a wall as it attempts to enter into Catia-type accounts while also cannibalizing Catia revenue. There will also continue to be technical limitations that exist today in Solidworks for complex parts and very large assemblies. These occur when you don't own the kernel you run on.
Solidworks "V6" is not only in its infancy at this time but is built on the Catia modeling kernel. It is unlikely that existing Solidworks users will adopt V6 for a while. If/when they do, data will most likely not be compatible. Dassault is really hoping that Solidworks customers get to the point where they just simply move to Catia V6 even though it will have data incompatibilities.
This discussion has been going on for 3 years now:
https://forum.solidworks.com/message/259368
The above information was emailed to be my a PTC Application Engineer Fellow.