This is very interesting news. My wife has been using Reason for about 10 years, and she is very pleased that she will now be able to use her Korg M1 and Wavestation VST's from within Reason. (Up until now, she had been playing these VST's standalone in realtime.) The Reason platform has been very stable and trouble-free for her.
I have been a Sonar user since the '80's, and I must admit that this development makes Reason seem like an attractive alternative to Sonar for me. The foibles that are often introduced with the well-meaning Monthly Sonar upgrades reveal that the regression test effort for many releases is inadequate and/or not thorough. I don't really expect them to be, given this timetable. Also, it has been 1.5 years since I have purchased Rapture Pro, and I am still unable to use it, with Sonar technical support only responding to my initial trouble report about every 6-9 months or so. (They contacted me in January and asked me if I still needed help, to which I replied, "yes! yes! yes!" I have not heard from then since.) I am often afraid to upgrade, and I have not experienced that kind of fear with any other software application, although I admit that Sonar is among the most complex.
Now, I won't expect technical support from Propellerhead, but if my wife's experience is any indication, it will not be required. Every upgrade she has purchased, although not monthly, has been a quality bug-free release. Hopefully that quality will continue when VST support is implemented.