The fully integrated sketchup plugin (just like the other plugins) will require both a standalone AND sketchup plugin license.
So you will only need to buy the sketchup plugin license when it comes out and use your existing standalone license.
In the meantime there is an exporter that you can use ...

If we hae bought the stand-alone plugin to exclusively use with Sketchup will we have to re-purchase the Sketchup plugin again?