MIR will "Host" other VSTi's in the future. I could be wrong, but I don't think VSL has any interest in having MIR hosted inside of other applications. MIR is in fact a "master host" application. Instead of hosting MIR inside of Kontakt 3 or the likes of those 3rd parties, you will be hosting them into MIR.
So you won't be opening up Cubase, and installing 2-3 or 4 "channel plug-ins" of MIR. It will be completely independent on it's own. You can (will be able to) host all your VSTi's inside of MIR, then output the audio into a DAW. That's at least how I see it and have read it thus far.
I am sure VSL will correct if this is not right.
Maestro2be